Sivarathri (night dedicated to adoration of Lord Siva) is observed every month and Mahasivarathri is celebrated once a year in late February or March on the fourteenth night of the new moon. The waning of the moon is the symbol for the waning of the mind. Lord Shiva, one of the Hindu trinity is revered as the destroyer of ignorance that arises from the mind. So during this most auspicious time, engaging in various spiritual practices to invoke Lord Siva's grace and benediction ensures success in achieving mastery over the mind.
We have not only the Mahasivarathri once a year, we have a Sivarathri every month, dedicated to the worship of Siva. And, why is the rathri (the night), so important? The night is dominated by the Moon. The Moon has 16 kalas (fractions of divine glory), and each day or rather night, during the dark fortnight, one fraction is reduced, until the entire Moon is annihilated on New Moon night. From then on, each night, a fraction is added, until the Moon is full circle on Full Moon Night. The Moon is the presiding deity of the mind; the mind waxes and wanes, like the Moon. “Chandrama-manaso jaathah” -- Out of the mind of the Purusha (Supreme Being), the Moon was born.
It must be remembered that the chief aim of all sadhana (spiritual striving) is to eliminate the mind, to become a-manaska. Then only can maya (illusion) be rent asunder and the Reality revealed. During the dark fortnight of the month, sadhana has to be done to eliminate each day a fraction of the mind, for, every day, a fraction of the Moon too is being taken out of cognisance. On the night of Chathurdhasi, the 14th day, the night of Siva, only a fraction remains. If some special effort is made that night, through more intensive and vigilant sadhana, like puja or japam or dhyana (ritual worship, one-pointed repetition & holy names, and meditation), success is ensured. Siva alone has to be meditated upon that night without the mind straying towards thoughts of sleep or food. This has to be done every month; once a year, on Mahaasivarathri a special spurt of spiritual activity is recommended, so that what is shavam (corpse) can become Sivam (God), by the perpetual awareness of its Divine Indweller.
Sathya Sai Speaks V09:03, Sivarathri Day, February 14, 1969
Sathya Sai Baba has taught that every ritual has a spiritual significance if one pays special attention to its inner meaning and significance. Mahasivarathri-The Inner Significance is a compilation of Sathya Sai Baba's discourses on the essence and significance of Mahasivarathi and its rituals. This compilation dives deep into the formless aspect of divinity embodied in the auspicious form of Lingam and stories from scriptures.