In plain words
We do not stop to think what it is in this life that is shrinking. Our life is filled out only along with our span of years. As much as our body goes on growing, so much does our span of life go on shrinking. Today we go on rejoicing greatly at sunrise and sunset. When the sun rises, they rejoice: "Aha! The sun has risen, the light has come; now we will begin our work." But the moment the sun sets: "Aha! Now we can sleep in peace. We can give the body proper rest," and we rejoice. This is only the effect of ignorance. However much we rejoice at sunrise and sunset, that sunrise and that sunset, both of them, are carrying away the measure of our life. This we do not stop to consider. So every human being must fulfil his duty before sunrise and sunset. Rāmakṛṣṇa Paramahaṃsa, too, went on struggling from dawn until night for that divine vision. Before lying down to sleep he would look this way and that. "Ayyo! Today too has gone to waste! Today too my Kṛṣṇa does not appear to me," he would say, and lie down in sorrow. Taking each day to be a moment, they suffered in many ways for that divine experience. In the past, all the great ṛṣis turned such yearning itself into tapas and went on experiencing the divine principle of the Ātma.
What is tapas? It is not merely to put the head down and the legs up and take on some kind of vow. Purity in the three instruments. To make mind, speech and body one is itself tapas. That itself is the greatness of the great souls.
In mind, one; in speech, one; in deed, one: so are the great souls; in mind, another; in speech, another; in deed, yet another: so are the wicked.
One thing in the mind, another in the word, yet another in the deed: this is not tapas at all. It turns into tamas. Humanness is very precious. It is very sacred. It is fit to be experienced. It is fit to be enjoyed. Jantūnāṃ narajanma durlabhame. Since human birth, so hard to gain, has come to us, we must enjoy it in the gaining of what has not yet been gained, and not waste it in gaining what is wicked. There is nothing wrong in studying all the worldly branches of learning.