I was reading Schopenhauer's History of Philosophy last night when I discovered the old crank railing against Spinoza for "his as unworthy as false deliverances about animals." From assertions in the Ethics Schopenhauer concludes, "Dogs [Spinoza] seems not to have known at all. To the monstrous proposition with which the 26th appendix [of the Ethics] opens...the best answer is given by a Spanish literateur of our day (Larra, psuedonym Figaro), 'He who has never kept a dog does not know what it is to love and be loved.'"
I spent two hours rooting around my apartment for a copy of Spinoza's Ethics in order to locate the passage that so offended Schopenhauer. Here it is: "Besides men, we know of no particular thing in nature in whose mind we may rejoice, and whom we can associate with ourselves in friendship or any sort of fellowship; therefore, whatsoever there be in nature besides man, a regard for our advantage does not call on us to preserve, but to preserve or destroy according to its various capabilities, and to adapt to our use as best we can."
I'm officially on the side of Schopenhauer in this important argument, by the way, and was pleased to later run across this additional tribute to dogs (in his own splendid Ethics): "Hence comes the four-legged friendships of so many of the better kind of men, for on what indeed should one refresh oneself from the endless deceit, falseness, and cunning of men if it were not for the dogs into whose faithful countenance one may look without distrust?"