It is not impossible that a terrier whose pleasure was concerned would perceive those amiable signs and know their meaning--know why his master stood in a peculiar way, talked with alacrity, and even had a peculiar gleam in his eye, so that on the least movement toward the door, the terrier would scuttle to be in time. 
Just as a terrier may perceive its master's purpose by the slightest signs, and scuttle to the door ready to go out, so