Question: what is the idiomatic expression of knowledge?
Answer:  Knowledge is power. ... 
 Know the ropes, learn the ropes. ... 
 Can't make heads or tails of it. ... 
 Burning the midnight oil, pull an all-nighter. ... 
 Know something backwards and forwards (or inside out), know the ins and outs. ... 
 Doing your homework. ... 
 Under one's belt. ... 
 Two heads are better than one, put our heads together.