If someone is fearing that their strength will fail them, it means they are worried that they will not be able to do something, whereas, if someone is fearing that their strength will increase, it means they are worried that they will become too powerful.
Consider the staetement "Fearing lest his strength should increase.". Based on this statement, is "Fearing lest his strength should  fail  him ," a true statement? Yes/no/unknown