Sentence:  Instead , he constantly became lost in parts and components of them , confused some of their details with those of neighboring objects , and so on , unless he allowed time to `` trace '' the object in question through minute <WSD>movements</WSD> of the head and hands and in this way to discover its contours . 
Meaning of the word marked with <WSD> tags:  a natural event that involves a change in the position or location of something