Sentence:  We should not allow the image of an immanent end brought about indirectly by our own action in the continuing human struggle for a just endurable order of existence to blind us to the fact that in some measure accelerating the end of our lease may be one consequence among others of many other of mankind 's thrusts toward we <WSD>know</WSD> not what future . 
Meaning of the word marked with <WSD> tags:  know how to do or perform something