Sentence:  Practically all the people of Laos , he explained - about two million of them - are rice farmers , and the means and <WSD>motives</WSD> of modern war are as strange to them as clocks and steel plows . 
Meaning of the word marked with <WSD> tags:  the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior