"Satz an Sich" is a basic notion in Bolzano's "Wissenschaftslehre". It is introduced at the very beginning, in section 19. Bolzano first introduces the notions of proposition (spoken or written or thought or in itself) and idea (spoken or written or thought or in itself). "The grass is green" is a proposition ("Satz"): in this connection of words, something is said or asserted. "Grass", however, is only an idea ("Vorstellung"). Something is represented by it, but it does not assert anything. Bolzano's notion of proposition is fairly broad: "A rectangle is round" is a proposition — even though it is false by virtue of self-contradiction — because it is composed in an intelligible manner out of intelligible parts.