(Click to enlarge photo of Srila Prabhupada)
"One should learn gravity from the sea and the rivulet. The sea is always within its limits, in spite of the many rivers pouring water into it. Similarly, one should properly use the assets of life and not squander them for purposes that have no permanent value. Uncontrolled, sensuous persons play with the assets of the body and accumulate wealth. But the strength of the body should be used for self-realization, not for sense gratification.
Human beings have two kinds of temperament. Some are introspective, and the others are extravagant. Those who are extravagant are enamored of the external features of phenomenal beauty and have no insight into the whole manifestation. They are practically asleep to introspection, and thus they are unable to derive any permanent value from the assets of the human form of body. But one who has developed introspection is as grave as the sea. While those who are extravagant are calm and quiet in sleep, such grave persons use the full advantage of the human form of life.
Although the animal propensities of the body should be minimized, those who are extravagant temporarily overflow in material enjoyment. Nonetheless, as soon as the rainy season of life is over, they become as dry as dry river beds. Life is meant for the right cause, or sat—that which exists for all time. In the material world, nothing is sat, or eternal, but the bad bargain of the material world can be used for the best purpose. The mind dedicated to extravagance is a bad bargain, but one can make the best use of the mind by introspection."
(Light of the Bhāgavata Verse 7, Purport)