D.1. The Non-Uniform Distribution of Everything: Since it is impossible to substitute if all tastes and all resources are uniformly distributed, it follows that non-uniform distribution of at least one of the means or ends is universal.
E.1. If everyone prefers apples and oranges equally, and have the same number of apples as of oranges, it is impossible to exchange anything. However, if either tastes or quantities differ, we may transact. Thus, non-uniform distribution of at least one mean or end is prerequisite of formation of an exchange relation.
Specifically, there can be four equalities in a two agent, two commodities world. And at least one of them must be absent, if exchange is to take place. These are:
I have the same preference for apples as for oranges,
You and I have the same preferences regarding apples and oranges,
I have the same number of apples as of oranges,
You and I have the same numbers of apples and oranges.
In presence of these, no trade can take place, but in absence of any one of them, transaction can take place.