⓪ Fantasy is a fascinating and often beautiful world, but it can also be a very dangerous world in which it is wise to know one's way about, lest one get lost and cannot find the road back to the world of fact.

① We feared lest he (should) lose his way.

= We feared that he would lose his way

② We hid it for fear lest it might be stolen.

= We hid it for fear that it might be stolen.

③ She dreaded lest strength to endure might wholly forsake her.

④ There was danger lest the plan (should) become known.