Sentence:  Depicted , Cubist flatness is now almost completely assimilated to the literal , undepicted kind , but <WSD>at</WSD> the same time it reacts upon and largely transforms the undepicted kind - and it does so , moreover , without depriving the latter of its literalness ; rather , it underpins and reinforces that literalness , re-creates it . 
Meaning of the word marked with <WSD> tags:  at the same instant