My object is to question a recurrent claim made to the point that Thomas Reid (1710–1796) was hostile to ether theories and that this hostility had its source in his distinctive interpretation of the first of Newton's regulæ philosophandi. Against this view I will argue that Reid did not have any quarrel at all with unobservable or theoretical entities as such, and that his objections against actual theories concerning ether were scientific rather than philosophical, even when based on Newton's first rule. I argue further that Reid's insistence on Newton's rule concerns, not direct observation, but rather the notion of explanation itself.