(93.) It has been truly and forcibly urged, that the dismissal of prejudice is absolutely essential to the prosecution of science: and we may add, that if there be any branch of physical knowledge which more especially calls for this dismissal; or whose progress, more than that of any other, has been impeded by prejudice; it is that of natural history. We allude more especially to prejudices of opinion; since those of sense, however they may arise in other sciences, are subordinate to this. Natural history is a science of facts and of inferences. The former regard structure and economy; and as these, under favourable circumstances, can be investigated by every one, few prejudices of sense can arise respecting them. But when we proceed further, and attempt, from these facts, to draw inferences, the case is different. No principles having been yet established, by which the facts we know from experience can be generalised in such a way as to establish their mutual relation and dependence. Every naturalist therefore thinks he is at liberty to draw his own inferences, and to apply them to the systematic arrangement of the objects by which they are furnished. One, for instance, arguing from the flight of the bat, looks on it as that animal which constitutes the true passage from quadrupeds to birds. Another, looking to its general aspect, is disposed to place it among the mice, fortified by the general name given by the French to the whole tribe of chauve souris.