When you are in the act of creating, there is an implicit form that is going to ask to be brought forth, and you have to know how to recognize it.  So, as they say, you are to learn all the rules – and then you must forget them.  As the lyric factor is beginning to move you, the mind is supposed to watch for the emergent form, because anything that comes out of the proper ground of inspiration is formed already.  There is an implicit form intrinsic in it, and your job is to recognize it.  TMD 183