Not only the names of Jacob's sons are significant, but the names of their sons as well. Thus the names of the sons of Issachar express the activities of the tribe known for its learning above all the others. The oldest was called Tola, "worm"; as the silk worm is distinguished for its mouth, with which it spins, so also the men of the tribe of Issachar for the wise words of their mouth. The second is Puah, "madder plant"; as this plant colors all things, so the tribe of Issachar colors the whole world with its teachings. The third is Jashub, "the returning one," for through the teachings of Issachar Israel will be turned back to its Heavenly Father; and Shimron, the fourth, is "the observing one," to indicate that the tribe of Issachar observes the Torah.