Sentence:  A borderline schizophrenic young man told me that to him the various theoretical concepts about which he had been expounding , in a most articulate fashion , during session after session with me , <WSD>were</WSD> like great cubes of almost tangibly solid matter up in the air above him ; as he spoke I was reminded of the great bales of cargo which are swung , high in the air , from a docked steamship . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)