To analyse and classify all the vagaries of the human imagination which may be comprehended under the denomination of humour, is no easy task, and as it is multiform we may stray into devious paths in pursuing it. But vast and various as the subject seems to be, there cannot be much doubt that there are some laws which govern it, and that it can be brought approximately under certain heads. It seems to be as generally admitted that there are different kinds of humour as that some observations possess none at all. Moreover, when remarks of a certain kind are made, especially such as show confusion or exaggeration, we often seem to detect some conditions of humour, and by a little change are able to make something, which has more or less the character of a jest. There is in this investigation a very formidable "Dweller on the Threshold." We contend with great disadvantages in any attempts to examine our mental constitution. When we turn the mind in upon itself, and make it our object, the very act of earnest reflection obscures the idea, or destroys the emotion we desire to contemplate. This is especially the case in the present instance. The ludicrous, when we attempt to grasp it, shows off its gay and motley garb, and appears in grave attire. It is only by abstracting our mind from the inquiry, and throwing it into lighter considerations, that we can at all retain the illusion. A clever sally appears brilliant when it breaks suddenly upon the mental vision, but when it is brought forward for close examination it loses half its lustre, and seems to melt into unsubstantial air. Humour may be compared to a delicate scent, which we only perceive at the first moment, or to evanescent beauty-- "For every touch that wooed its stay Has brushed its brightest hues away." This last simile is especially in point here, and the quotations in this book will scarcely be found humorous, so long as they are regarded as mere illustrations of the nature of humour. We need not--taking these matters into consideration--feel much surprised that some people say the ludicrous cannot be defined; as for instance, Buckingham, "True wit is everlasting like the sun, Describing all men, but described by none;" and Addison:--"It is much easier to decide what is not humorous than what is, and very difficult to define it otherwise than Cowley has done, by negatives"--the only meaning of which is that the subject is surrounded with rather more than the usual difficulties attending moral and psychological researches. Similar obstacles would be encountered in answering the question, "What is poetry?" or "What is love?" We can only say that even here there must be some surroundings by which we can increase our knowledge.