The terms "substance" and "form" are used often in New Christian thought. What do they mean?
The substance of a thing is its essential "thingness", its being or essence, which exists at an interior level. We usually think of form as shape, and in some senses that's correct: a potter shapes a vase out of clay, and we see it as a graceful hollow shape, and may imagine flowers in it. Similarly, a house has a shape, and from its shape we may even name it, as a ranch or colonial house. But if we think a little more deeply we can see a house as the place where a family may live, and if it is well taken care of, we can suppose that the family may cherish it as a home, and if we see indications that there are children living there, in our minds we can imagine love and closeness there. The house, by these indications, becomes a form or external expression of the love and security that we understand may be within it.
In the Word the idea of forms is used this way. The ordered camp of Israel with the tabernacle in its midst, described in Numbers 2, is a form of an orderly and worshipful human mind. The woman clothed with the sun, pictured in Revelation 12:1, is the form and representation of the new church the Lord is forming. The man-child she brings forth is the form of that church's doctrine. A form is an external that we can easily picture that contains the essence of an abstract idea that is more difficult to grasp, and it connects the internal usefulness of the abstract directly to the external usefulness of the external or tangible form.
Substance and form work together. A good love is brought into being via forming an action.
We use this concept all the time when we talk. Our loves are substances, and they are formed into thoughts, and then into words. As long as we are speaking sincerely, the emotion, the thought and the spoken word can be seen as one united thing.