Second Stage Lensmen by E.E. Smith

Kinnison had not underestimated the power and capacity of his as yet unknown opposition. Well it was for him and for his Patrol that he was learning to think; for, as has already been made clear, this phase of the conflict was not essentially one of physical combat. Material encounters did occur, it is true, but they were comparatively unimportant. Basically, fundamentally, it was brain against brain; the preliminary but nevertheless prodigious skirmishing of two minds -- or, more accurately, two teams of minds -- each trying, even while covering up its own tracks and traces, to get at and to annihilate the other.

Each had certain advantages.