The German Ideology?

The passage that I found particularly difficult to comprehend is in the middle of page 19. “The relation of the productive forces to the form of intercourse is the relation of the form of intercourse to the occupation or activity of the individuals. (The Fundamental form of this activity is, of course, material, from which depend all other forms-mental, political, religious, etc. The various shaping, of material is, of course, in every case dependent on needs which are already developed, and both the production and the satisfaction of these needs is an historical process, which is not found in the case of a sheep or a dog [perversity of Stirner’s principal argument adversus hominen], although sheep and dogs in their present form certainly, but malgré eux, are products of an historical process.)

I probably had difficulties comprehending this text because I was unable to fully interpret the passages before this one and I didn’t find a very good definition of a few words and concepts.