There is also another class of arguments which is derived from traces of a fact, as a weapon, blood, an outcry which has been raised, trepidation, changes of complexion, inconsistency of explanation, trembling, or any of these circumstances which can be perceived by our senses, or if anything appears to have been prepared, or communicated to any one, or if anything has been seen or heard, or if any information has been given.

But of probabilities some influence us separately by their own weight, some, although they appear trifling by themselves, still, when all collected together, have great influence.  And in such probabilities as these there are sometimes some unerring and peculiar distinguishing characteristics of things.  But what produces the surest belief in a probability is, first of all, a similar instance, then the similarity of the present case to that instance sometimes even a fable, though it is an incredible one, has its influence, nevertheless, on men’s minds.

XII. C.  F. What next?  What is the principle of definition, and what is the system of it?

C.  P. There is no doubt but that definition belongs to the genus, and is distinguishable by a certain peculiarity of the characteristics which it mentions, or else by a number of common circumstances, from which we may extract something which looks like a peculiar property.  But since there is often very great disagreement about what are peculiar properties, we must often derive our definitions from contraries, often from things dissimilar, often from things parallel.  Wherefore descriptions also are often suitable in this kind of address, and an enumeration of consequences, and above all things, an explanation of the names and terms employed, is most effectual.

C.  F. You have now then explained nearly all the questions which arise about a fact, or about the name given to such fact.  The next thing is, when the fact itself and its proper title are agreed upon, that a doubt arises as to what its character is.

C.  P. You are quite right.

C.  F. What divisions, then, are there in this part of the argument?

C.  P. One urges either that what has been done has been lawfully done, for the sake either of warding off or of avenging an injury, or under pretext of piety, or chastity, or religion, or one’s country, or else that it has been done through necessity, out of ignorance, or by chance.  For those things which have been done in consequence of some motion or agitation of the mind, without any positive intention, have, in legal proceedings, no defence if they are impeached, though they may have an excuse if discussed on principles unfettered by strict rules of law.  In this class of discussion, in which the question is, what the character of the act is, one inquires, in the terms of the controversy, whether the act has been rightly and lawfully done or not; and the discussion on these points turns on a definition of the before-mentioned topics.