Sentence:  Everywhere else his <WSD>ideas</WSD> lay or hung in visible form : his models , drawings , ten foot canvases in monochromes from his painting days , and underfoot a windfall of broken-backed books that looked as though their insides had been ransacked by a maniac . 
Meaning of the word marked with <WSD> tags:  the content of cognition; the main thing you are thinking about