Isaac Husik, A History of Mediaeval Jewish Philosophy
“ The vegetative soul comes from certain spheral influences, themselves due to the universal soul, and ultimately to the will of God. It is the first of the three to make its appearance in the body. It is already found in the embryo, to which it gives the power of motion in its own place like the motion of a plant or tree. Its seat is in the liver, where the growth of the embryo begins. Its function ceases about the twentieth year, when the growth of the body reaches its limit. ”
