The Purpose of the Elder:

 

The Elder are, on one level, merely a repeating function, a recurring motif.
They represent a Fourfold System of Balance,
analogous to the Elements of Classical Philsophy
and the Suits of the Tarot Deck.

The Elder are a force for order in the universe,
incarnated as four individual forces for chaos.

Each of the Elder has its own purposes, but each of these purposes,
both in itself and in opposition to the other three,
serves the overall balance.

Order emerges as a result of the balance of four equidistant pulls toward
Chaos, each one as strong as the others.

Thus, the purpose of the Elder is to maintain the order of the universe,
and to a lesser extent, to rebalance its random unjustices.