chapter  1
The functions of money
Pages 11

A common unit of account, and prices expressed in such a unit, render comparable goods and services not otherwise comparable; and such comparability is apparently necessary if the individual's choice is to be rational, in the sense of implying a transitive (i .e., non-contradictory) ordering of preferences. There is little information on this subject so far but some experimental evidence indicates that human choice often becomes intransitive in areas where it is not facilitated by a common unit of account.! To value things in money terms is man's way of formulating and ordering his preferences; without its help even the consumer's simple decisions can easily become irrational.