"WHY CELEBRATE MAHA SHIV RATRI ?"

before answering the question let me first touch upon some things which i would request the aryas to reflect upon.

How are words different from pictures ? Dont pictures or symbols have the power to communicate that which words can ?
Is the saying - a picture is worth a thousand words - wrong ? Are wordy details more communicative than graphs ?

the whole idea of opposing symbols and forms is meaningless.They are external aids for inner reflection in spiritual endeavors ..a written or spoken word is no different than a symbol or ritual on the exterior.
What matters is the reflection that goes within along with what we do externally , be it hearing vedas or performing rituals infront of a symbol

The hindu rituals are meant to be observed in the same spirit and Shivaratri is no exception.

[ The only valid opposition to rituals is when the spirit or purpose of the ritual is lost as was encountered by Swami Dayanand ji at his home]

1) First lets see how the Vedas paint a picture of Shiva

त्र्यम्बकं यजामहे सुगन्धिं पुष्टिवर्धनम्।
उर्वारुकमिव बन्धनान्मृत्योर्मुक्षीय मामृतात्॥
Rig Ved 7:59:12
"Three eyed" !

Sri Rudram (Krishna Yajur Veda Sri Rudram anuvak 5)
नमो भवाय च रुद्राय च
नमः शर्वाय च पशुपतये च
नमो नीलग्रीवाय च शितिकण्ठाय च
नमः कपर्दिने च व्युप्तकेशाय च

"pashupati , neel kanth , matted hair, clean shaven" !

What's all this in the Veda ? its nothing but a painting of Shiva in Words ! If hindus paint the same picture with brush or sculpture it does not become anti-vedic

2) Maha Shivratri

I cannot say it any better than Swami Sivanadna Ji who describes this in detail

Introduction

This falls on the 13th (or 14th) day of the dark half of Phalgun (February-March). The name means "the night of Shiva". The ceremonies take place chiefly at night. This is a festival observed in honour of Lord Shiva. Shiva was married to Parvati on this day.

People observe a strict fast on this day. Some devotees do not even take a drop of water. They keep vigil all night. The Shiva Lingam is worshipped throughout the night by washing it every three hours with milk, curd, honey, rose water, etc., whilst the chanting of the Mantra Om Namah Shivaya continues. Offerings of bael leaves are made to the Lingam. Bael leaves are very sacred as, it is said, Lakshmi resides in them.

Hymns in praise of Lord Shiva, such as the Shiva Mahimna Stotra of Pushpadanta or Ravana's Shiva Tandava Stotra are sung with great fervour and devotion. People repeat the Panchakshara Mantra, Om Namah Shivaya. He who utters the Names of Shiva during Shivaratri, with perfect devotion and concentration, is freed from all sins. He reaches the abode of Shiva and lives there happily. He is liberated from the wheel of births and deaths. Many pilgrims flock to the places where there are Shiva temples.
The Story of King Chitrabhanu

In the Shanti Parva of the Mahabharata, Bhishma, whilst resting on the bed of arrows and discoursing on Dharma, refers to the observance of Maha Shivaratri by King Chitrabhanu. The story goes as follows.

Once upon a time King Chitrabhanu of the Ikshvaku dynasty, who ruled over the whole of Jambudvipa, was observing a fast with his wife, it being the day of Maha Shivaratri. The sage Ashtavakra came on a visit to the court of the king.

The sage asked, "O king! why are you observing a fast today?"

King Chitrabhanu explained why. He had the gift of remembering the incidents of his previous birth.

The king said to the sage: "In my past birth I was a hunter in Varanasi. My name was Suswara. My livelihood was to kill and sell birds and animals. One day I was roaming the forests in search of animals. I was overtaken by the darkness of night. Unable to return home, I climbed a tree for shelter. It happened to be a bael tree. I had shot a deer that day but I had no time to take it home. I bundled it up and tied it to a branch on the tree. As I was tormented by hunger and thirst, I kept awake throughout the night. I shed profuse tears when I thought of my poor wife and children who were starving and anxiously awaiting my return. To pass away the time that night I engaged myself in plucking the bael leaves and dropping them down onto the ground.

"The day dawned. I returned home and sold the deer. I bought some food for myself and for my family. I was about to break my fast when a stranger came to me, begging for food. I served him first and then took my food.

"At the time of death, I saw two messengers of Lord Shiva. They were sent down to conduct my soul to the abode of Lord Shiva. I learnt then for the first time of the great merit I had earned by the unconscious worship of Lord Shiva during the night of Shivaratri. They told me that there was a Lingam at the bottom of the tree. The leaves I dropped fell on the Lingam. My tears which I had shed out of pure sorrow for my family fell onto the Lingam and washed it. And I had fasted all day and all night. Thus did I unconsciously worship the Lord.

"I lived in the abode of the Lord and enjoyed divine bliss for long ages. I am now reborn as Chitrabhanu."
Spiritual Significance of the Ritual

The Scriptures record the following dialogue between Sastri and Atmanathan, giving the inner meaning of the above story.

Sastri: It is an allegory. The wild animals that the hunter fought with are lust, anger, greed, infatuation, jealousy and hatred. The jungle is the fourfold mind, consisting of the subconscious mind, the intellect, the ego and the conscious mind. It is in the mind that these "wild animals" roam about freely. They must be killed. Our hunter was pursuing them because he was a Yogi. If you want to be a real Yogi you have to conquer these evil tendencies. Do you remember the name of the hunter in the story?

Atmanathan: Yes, he was called Suswara.

Sastri: That's right. It means "melodious". The hunter had a pleasant melodious voice. If a person practices Yama and Niyama and is ever conquering his evil tendencies, he will develop certain external marks of a Yogi. The first marks are lightness of the body, health, steadiness, clearness of countenance and a pleasant voice. This stage has been spoken of in detail in the Swetaswatara Upanishad. The hunter or the Yogi had for many years practised Yoga and had reached the first stage. So he is given the name Suswara. Do you remember where he was born?

Atmanathan: Yes, his birthplace is Varanasi.

Sastri: Now, the Yogis call the Ajna Chakra by the name Varanasi. This is the point midway between the eyebrows. It is regarded as the meeting place of the three nerve currents (Nadis), namely, the Ida, Pingala and the Sushumna. An aspirant is instructed to concentrate on that point. That helps him to conquer his desires and evil qualities like anger and so on. It is there that he gets a vision of the Divine Light within.

Atmanathan: Very interesting! But how do you explain his climbing up the bael tree and all the other details of the worship?

Sastri: Have you ever seen a bael leaf?

Atmanathan: It has three leaves on one stalk.

Sastri: True. The tree represents the spinal column. The leaves are threefold. They represent the Ida, Pingala and Sushumna Nadis, which are the regions for the activity of the moon, the sun and fire respectively, or which may be thought of as the three eyes of Shiva. The climbing of the tree is meant to represent the ascension of the Kundalini Shakti, the serpentine power, from the lowest nerve centre called the Muladhara to the Ajna Chakra. That is the work of the Yogi.

Atmanathan: Yes, I have heard of the Kundalini and the various psychic centres in the body. Please go on further; I am very interested to know more.

Sastri: Good. The Yogi was in the waking state when he began his meditation. He bundled up the birds and the animals he had slain and, tying them on a branch of the tree, he rested there. That means he had fully conquered his thoughts and rendered them inactive. He had gone through the steps of Yama, Niyama, Pratyahara, etc. On the tree he was practising concentration and meditation. When he felt sleepy, it means that he was about to lose consciousness and go into deep sleep. So he determined to keep awake.

Atmanathan: That is now clear to me; you certainly do explain it very well. But why did he weep for his wife and children?

Sastri: His wife and children are none other than the world. One who seeks the Grace of God must become an embodiment of love. He must have an all-embracing sympathy. His shedding of tears is symbolical of his universal love. In Yoga also, one cannot have illumination without Divine Grace. Without practising universal love, one cannot win that Grace. One must perceive one's own Self everywhere. The preliminary stage is to identify one's own mind with the minds of all created beings. That is fellow-feeling or sympathy. Then one must rise above the limitations of the mind and merge it in the Self. That happens only in the stage of Samadhi, not earlier.

Atmanathan: Why did he pluck and drop the bael leaves?

Sastri: That is mentioned in the story only to show that he had no extraneous thoughts. He was not even conscious of what he was doing. All his activity was confined to the three Nadis. The leaves, I have said before, represent the three Nadis. He was in fact in the second state, namely, the dream state, before he passed into the deep sleep state.

Atmanathan: He kept vigil the whole night, it is said.

Sastri: Yes, that means that he passed through the deep sleep state successfully. The dawning of day symbolises the entrance into the Fourth state called Turiya or superconsciousness.

Atmanathan: It is said that he came down and saw the Lingam. What does that mean?

Sastri: That means that in the Turiya state he saw the Shiva Lingam or the mark of Shiva in the form of the inner lights. In other words, he had the vision of the Lord. That was an indication to him that he would realise the supreme, eternal abode of Lord Shiva in course of time.

Atmanathan: So it appears from what you say that the sight of the lights is not the final stage?

Sastri: Oh no! That is only one step, albeit a difficult one. Now think of how the story continues. He goes home and feeds a stranger. A stranger is one whom you have not seen before. The stranger is no other than the hunter himself, transformed into a new person. The food was the likes and dislikes which he had killed the previous night. But he did not consume the whole of it. A little still remained. That was why he had to be reborn as King Chitrabhanu. Going to the world of Shiva (Salokya) is not enough to prevent this. There are other stages besides Salokya. These are Samipya, Sarupya and finally Sayujya. Have you not heard of Jaya and Vijaya returning from Vaikunta?

Atmanathan: Yes, I have understood now.
Lord Shiva's Assuarance

When creation had been completed, Shiva and Parvati went out to live on the top of Mount Kailas. Parvati asked, "O venerable Lord! which of the many rituals observed in Thy honour doth please Thee most?"

The Lord replied, "The 14th night of the new moon, in the dark fortnight during the month of Phalgun, is my most favourite day. It is known as Shivaratri. My devotees give me greater happiness by mere fasting than by ceremonial baths and offerings of flowers, sweets and incense.

"The devotee observes strict spiritual discipline in the day and worships Me in four different forms during each of the four successive three-hour periods of the night. The offering of a few bael leaves is more precious to Me than the precious jewels and flowers. My devotee should bathe Me in milk at the first period, in curd at the second, in clarified butter at the third, and in honey at the fourth and last. Next morning, he should feed the Brahmins first and, after performing the prescribed ceremonies, he can break his fast. O Parvati! there is no ritual which can compare with this simple routine in sanctity."

Parvati was deeply impressed by the speech of Loid Shiva. She repeated it to Her friends who in their turn passed it on to the ruling princes on earth. Thus was the sanctity of Shivaratri broadcast all over the world.

The two great natural forces that afflict man are Rajas (the quality of passionate activity) and Tamas (that of inertia). The Shivaratri Vrata aims at the perfect control of these two. The entire day is spent at the Feet of the Lord. Continuous worship of the Lord necessitates the devotee's constant presence in the place of worship. Motion is controlled. Evils like lust, anger, and jealousy, born of Rajas are ignored and subdued. The devotee observes vigil throughout the night and thus conquers Tamas also. Constant vigilance is imposed on the mind. Every three hours a round of worship of the Shiva Lingam is conducted. Shivaratri is a perfect Vrata.

The formal worship consists of bathing the Lord. Lord Shiva is considered to be the Form of Light (which the Shiva Lingam represents). He is burning with the fire of austerity. He is therefore best propitiated with cool bathing. While bathing the Lingam the devotee prays: "O Lord! I will bathe Thee with water, milk, etc. Do Thou kindly bathe me with the milk of wisdom. Do Thou kindly wash me of all my sins, so that the fire of worldliness which is scorching me may be put out once for all, so that I may be one with Thee-the One alone without a second."

At the Sivananda Ashram, Rishikesh, the Shivaratri festival is celebrated in the following manner.

All spiritual aspirants fast the whole day, many of them without taking even a single drop of water.
A grand havan is performed for the peace and welfare of all.
The whole day is spent in doing the Japa of Om Namah Shivaya and in meditation upon the Lord.
At night all assemble in the temple and chant Om Namah Shivaya the whole night.
During the four quarters of the night the Shiva Lingam is worshipped with intense devotion.
Sannyas Diksha is also given on this day to sincere seekers on the path.

Offer this inner worship to Lord Shiva daily: "I worship the jewel of my Self, the Shiva residing in the Lotus of my heart. I bathe Him with the water of my pure mind brought from the river of faith and devotion. I worship Him with the fragrant flowers of Samadhi-all this so that I may not be born again in this world."

Here is another formula for the supreme worship of the Lord: "O Shiva! you are my Self. My mind is Parvati. My Pranas are your servants. My body is your house. My actions in this world are your worship. My sleep is Samadhi. My walk is circumambulation of you. My speech is your prayer. Thus do I offer all that I am to you.

source : http://www.dlshq.org/religions/shivaratri.htm