Lydia starts by describing a phenomenon: red squirrels make holes in the bark of sugar maple trees and consume their sap. She lays out two alternative explanations for this phenomenon: the squirrels are seeking either water or sugar, which are the two main components of sugar maple sap. Lydia then rules out the possibility that they are seeking water, since water is more easily available from other sources. Thus, Lydia concludes the explanation for this behavior is that the squirrels are seeking sugar.

Lydia reaches her conclusion by a process of elimination. She states two alternative explanations for the squirrels' behavior, then eliminates one of them — the idea that the squirrels are seeking water — which leaves the other one, the sugar hypothesis, remaining.