Money could not be converted into capital if wage labour did not exist. David Harvey
Just as there are Laws of Conservation of Matter and Energy, so there are in fact Laws of Conservation of Pain and Joy. Neither can ever be created or destroyed. But one can be converted into the other. Spider Robinson
From the moment when labour can no longer be converted into capital, money, or rent, into a social power capable of being monopolized, i.e., from the moment when individual property can no longer be transformed into bourgeois property, into capital, from that moment, you say individuality vanishes. Friedrich Engels
Money cannot be converted into houses or trained teachers or hospitals at the touch of a magic wand. There are limitations to our physical and intellectual resources. John James Cowperthwaite
Society as a whole must be converted into a gigantic school. Che Guevara
Some memorizers arbitrarily associate each playing card with a familiar person or object, so that the king of clubs is represented by, say, Tony Danza. The grand masters associate each card with a person, an action, or an object so that every group of three cards can be converted into a sentence. Joshua Foer