But there is an alternative--although amusing objects and circumstances are almost innumerable, as we may have gathered from the last chapter, we may claim a license, frequently allowed in other cases, of drawing conclusions from a considerable number of promiscuous examples, and regarding them as a fair sample of the whole. Such a view has no doubt been taken by many able men, who have attempted to define the ludicrous. An eminent German philosopher even said that he did not despair of discovering its real essence. It must be admitted that we have no actual proof that the provocatives of the ludicrous are innumerable or utterly heterogeneous, nor any greater presumption that they are so than in many cases of physical phenomena which we are accustomed to define. The difficulty is at the most only that of degree, but we are unusually conscious of it owing to the nature of the subject. Every day, if not every hour, brings ludicrous objects of different kinds before us, whereas the number and variety of plants, animals, and minerals are only known to botanists and zoologists and other scientific men. As the members of a class are infinitely less numerous than the somewhat similar things which lie outside it, the course commonly adopted has been to examine a few members of it and try to find some of the properties a class possesses, without aspiring to ascertain them all. Our conclusions will thus be coextensive with our knowledge, rather than with our wishes, incomplete and overwide rather than illogical. How far easier is it, with regard to our present subject, to decide that the circumstances which awaken the ludicrous possess certain elements, than that it requires nothing more! the chemist may analyse the bright water of a natural spring which he can never manufacture. We can sometimes form what is humorous by imitation, but not by following any rules or directions; we even seem to be led more to it by accident than by design. Our safest plan, therefore, will be to search for some possible elements, and to endeavour to establish some probabilities on a subject which must always be somewhat surrounded with uncertainty. The constant tillage of the soil, the investigations made, and definitions attempted, have not been unproductive of fruit, and we may feel a tolerable degree of assurance on some points in question, while admitting that, however assiduously we labour, there will always be something beyond our reach. We will proceed then to examine and compare the stores of our predecessors, and if possible add a grain to the heap. Knowledge is progressive, and although it is not the lot of man to be assured of absolute truth, still the acquisition of what is relative or approximate is not valueless. This consideration, which has cheered many on the road of physical philosophy, may afford some encouragement to those who follow the equally obscure indications of our mental phenomena. CHAPTER XXI.