It is clear that there are two matters to every vessel: form and substance. For example, in an eye, the substance is the physical vessel of the eye, whereas the form is the spiritual power of sight. In a brain, the substance is the physical organ of the brain, whereas the form is the spiritual power to think etc. It is clear that the substance of the eye limits the spiritual form of the eye which is the power of sight. Nonetheless, somehow, the substance of the eye is patterned after the spiritual form for sight. Because of this it can contain it. It is because of this that it becomes a vessel to it, like a glove to the hand. Likewise, the physical substance of the brain limits the spiritual form which is the power to intellectualize. However, though the two are essentially different, the one being a spiritual heyulie and the other being a physical organ, nonetheless, the physical substance of the brain is somehow patterned after the spiritual form of the heyulie to think. It thereby is a vessel designed to contain it.
Now, the substance is made up of the “thickening” of the form. For example, ice is nothing more than “thickened” water. It is specifically when the water thickens that it loses its fluidity and becomes solid. Furthermore, it is the last level of form which becomes the first level of substance. For example, from the last level of the power of growth, actual physical growth comes about. Another example is that it is the last level of the soul which becomes invested in the physical body. A further example is that the physical power of sight comes from the last level of the spiritual power of sight. For this reason when a child grows, the spiritual growth of his intellect is simultaneous to the growth of his brain. The substance of the vessel grows according to the growth of the form, which is the light.