Thus we are led by various lines of thought to the same conclusion. It is certain that we can only learn what the uniformities (the laws) of nature are by _experience_, and in order to determine whether all the successions of events have been and now are universally uniform, we must have a _universal_ experience. If there have been deviations from general laws under peculiar conditions--if one form of energy has been counteracted and modified by another form of energy, or even by an intelligent Will, so as to give a _particular_ result--experience (= observation and testimony) must be just as adequate to attest the reality of that particular deviation as it is to attest the prevalence of general laws.[249] We have no intuitive and necessary conviction of the uniformity of nature, and therefore we can not affirm in an _à priori_ manner what is _possible_ or _impossible_. Those scientists who adopt the maxim of Faraday, that in the investigation of new and peculiar phenomena "we must set out with clear ideas of the possible and the impossible," are doomed to move in a vicious circle. They can not be sure that a fact of experience is a real fact until they have ascertained the laws of nature in the case, and they can not ascertain what the laws of nature are until they have ascertained the facts. They must not profess to have learned any thing until they have ascertained that it is possible, and they can not decide that it is possible until they have learned every thing, because the single item of knowledge they are deficient in may be the very principle which warrants a belief in the possibility of the fact. The maxim is obviously absurd. In its theological bearings it is repudiated even by Professor Tyndall, the pupil and successor of Faraday at the Royal Institution. "You never hear the really philosophical defenders of the doctrine of uniformity speaking of _impossibilities_ in nature. They never say ... that it is impossible for the Builder of the universe to alter his work. Their business is not with the possible, but with the actual."[250] The hypothesis under discussion is further vitiated by the assumption that laws are _causes_ adequate in themselves to the production of all phenomena. So that now Creation by Law (Nomogeny) is the watchword of this school of thinkers. The men who have defined law as "the uniformity of relations among phenomena"--as "an observed order of facts"--now speak of laws as having in themselves a real efficiency; as producing, regulating, and governing powers. Under this high-sounding phrase--"Creation by Law"--there is not only the artful concealment of a difficulty, but there is also the interpolation of a positive error. The _uniformities_ of natural phenomena are the _causes_ of phenomena, or, in other words, the order of nature is its own cause, which is not only erroneous but self-contradictory.