In plain words
Śānti is most essential. There must be Śānti in body and in mind. All that comes from the body is only reflection. So you must control, first of all, what comes from within. That itself is mastery of the senses. This is what they called kriyā yoga. To restrain our bad feelings and bad deeds: that itself is yoga. Only when we restrain these will feelings of God that are sacred, eternal and Satya, sacred feelings, spring up.
Students! Above all, at this age you must shape yourselves, as far as you can, into ideal beings. You must raise society to a still higher state. Today society is in great disorder. What is the reason? In society every person is doing imitation. Imitation is weakness. Creation is divine. There must be no imitation at all. Our students must be ideal students. They must achieve control of the senses. We must show forth ideal qualities. We must set society right. We must thoroughly wipe away the dirt that has gathered in society. This is precisely what we must do today. Having studied, do not scramble after a job. For what is udyoga? Yoga itself is udyoga. You must achieve this yoga. What is yoga? Service itself is yoga. We must take part in service to society. There is nothing higher than service to society. In ideal service to society, Ahaṅkāra is rooted out. Ahaṅkāra itself brings about man's downfall. When we take part in service, Ahaṅkāra falls away of itself. We must do service wholeheartedly. We must do service with a sacred feeling. We must do service that seeks no fruit. What is the fruit? Ānanda in society itself is the fruit. What fruit could we want beyond this? That itself is the form of God.
Eternal Ānanda, giver of the highest happiness, Jñāna itself in form, beyond the pairs of opposites, like the sky, reached by the meditation of the yogi's heart, one, eternal, stainless, unmoving, witness of every mind, beyond all feeling, free of the three guṇas...
This itself is eternal Ānanda. This itself is the Ānanda of yoga. This itself is the Ānanda of Advaita. This itself is the Ānanda of the Ātma.
Such Ānanda of the Ātma is not something to be had from anyone. It is natural to you. It is your own.