Sentence:  It <WSD>is</WSD> an over-all impression Mr. Sansom strives for , an impression compounded of visual details , of a savory mixture of smells , of much loving attention to architecture and scenery , of lights and shadows , of intangibles of atmosphere and of echoes of the past . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)