This taken from Sivananda excerp on Holi
All great Hindu festivals have religious, social and hygienic elements in them. Holi is no exception. Every season has a festival of its own. Holi is the great spring festival of India. Being an agricultural country, India's two big festivals come during the harvest time when the barns and granaries of our farmers are full and they have reason to enjoy the fruits of their hard labour. The harvest season is a festive season all over the world.
Man wants relaxation and change after hard work. He needs to be cheered when he is depressed on account of work and anxieties. Festivals like Holi supply him with the real food and tonic to restore his cheer and peace of mind.
The religious element in the Holi festival consists of worship of Sri Krishna. In some places it is also called the Dol Yatra. The word dol literally means "a swing". An image of Sri Krishna as a babe is placed in a little swing-cradle and decorated with flowers and painted with coloured powders. The pure, innocent frolics of little Krishna with the merry milkmaids—the Gopis of Brindavan—are commemorated. Devotees chant the Name of Sri Krishna and sing Holi-songs relating to the frolics of little Krishna with the Gopis.
The social element during Holi is the uniting or "embracing" of the great and the small, of the rich and the poor. It is also the uniting of equals. The festival teaches us to "let the dead bury the dead". We should forget the outgoing year's ill-feelings and begin the new year with feelings of love, sympathy, co-operation and equality with all. We should try to feel this oneness or unity with the Self also.
Holi also means "sacrifice". Burn all the impurities of the mind, such as egoism, vanity and lust, through the fire of devotion and knowledge. Ignite cosmic love, mercy, generosity, selflessness, truthfulness and purity through the fire of Yogic practice. This is the real spirit of Holi. Rise from the mire of stupidity and absurdity and dive deep into the ocean of divinity.
The call of Holi is to always keep ablaze the light of God-love shining in your heart. Inner illumination is the real Holi. The spring season is the manifestation of the Lord, according to the Bhagavad Gita. Holi is said there to be His heart.