SB 10.1.40

vrajaṁs tiṣṭhan padaikena
 yathaivaikena gacchati
yathā tṛṇa-jalaukaivaṁ
 dehī karma-gatiṁ gataḥ
Word for word: 
vrajan — a person, while traveling on the road; tiṣṭhan — while standing; padā ekena — on one foot; yathā — as; eva — indeed; ekena — by another foot; gacchati — goes; yathā — as; tṛṇa-jalaukā — a worm on a vegetable; evam — in this way; dehī — the living entity; karma-gatim — the reactions of fruitive activities; gataḥ — undergoes.
Translation: 
Just as a person traveling on the road rests one foot on the ground and then lifts the other, or as a worm on a vegetable transfers itself to one leaf and then gives up the previous one, the conditioned soul takes shelter of another body and then gives up the one he had before.
Purport: 

This is the process of the soul’s transmigration from one body to another. At the time of death, according to his mental condition, the living being is carried by the subtle body, consisting of mind, intelligence and ego, to another gross body. When higher authorities have decided what kind of gross body the living entity will have, he is forced to enter such a body, and thus he automatically gives up his previous body. Dull-minded persons who do not have the intelligence to understand this process of transmigration take for granted that when the gross body is finished, one’s life is finished forever. Such persons have no brains with which to understand the process of transmigration. At the present moment there is great opposition to the Hare Kṛṣṇa movement, which is being called a “brainwashing” movement. But actually the so-called scientists, philosophers and other leaders in the Western countries have no brains at all. The Hare Kṛṣṇa movement is trying to elevate such foolish persons by enlightening their intelligence so that they will take advantage of the human body. Unfortunately, because of gross ignorance, they regard the Hare Kṛṣṇa movement as a brainwashing movement. They do not know that without God consciousness one is forced to continue transmigrating from one body to another. Because of their devilish brains, they will next be forced to accept an abominable life and practically never be able to liberate themselves from the conditional life of material existence. How this transmigration of the soul takes place is very clearly explained in this verse.