It must be confessed that an adequate analysis of cognitive relatedness on scientific lines is not to be found in Spencer's works. I am not sure that it is yet to be found in the works of any other philosopher, though there are many signs that the difficult problems it involves are receiving serious attention. This much seems certain, for those who accept the spirit, though not perhaps the letter, of Spencer's teaching: that there it is as a constitutive mode of relatedness in the realm of nature, and that, if it forms part of the evolutionary scheme, if it is present in the conclusion, so far reached, though it was absent in the physico-chemical premises, if it is to be included in a philosophy of science it must be dealt with by that philosophy on lines strictly analogous to those on which any other relational problem is treated. Firmly as we may believe in the reality of Source, we must not call to our aid some psychic entity, some entelechy, some _elan vital_, to help us out of our difficulties; for one and all of these lie wholly outside the universe of discourse of science; and not one of them affords the smallest help in solving a single scientific problem in a manner that is itself scientific. We have seen that Spencer believed that the task of psychology is to investigate the correlation of external and internal relations, and, in that sense, itself to correlate them within a scientific interpretation. Now the outcome of the former correlation is some form of behaviour or conduct on the part of the organism. No doubt such behaviour affords data to be dealt with in subsequent cognition. But it implies the prior cognition which leads up to it; and it is this prior cognition, abstracted from the behaviour to which it leads, that we have to consider. It is so terribly complex that it is difficult to deal with it comprehensibly in a brief space. Let me, however, try to do so, at least in tentative outline. There occurs, let us say, an external event in the physical world, such as the motion of a billiard-ball across the table; and when during its progress this stimulates the retina, there is an internal physico-chemical process which runs its course in retina, optic nerves, and the central nervous system. We may regard these two processes, external and internal, as _so far_, of like physical order. With adequate knowledge the two could, in some measure, be serially correlated as such. But the physico-chemical processes in the organism are not only of this physical type. They are vital or physiological as well. And this makes a real difference. Of course this statement is open to question. But I, for one, believe that there are specific relations present in physiological processes, _qua_ vital, other than those of the physico-chemical type--relations which are effective and which require a distinctive name. So far I am a vitalist. At some stage of evolution these new modes of effective relatedness came into being, whereas in the