Now, if by common be meant what has been shared by all minds or the majority of minds up to a particular time, a moment's inspection of the process of correcting illusion will show that science assumes the possibility of a common illusion. In the history of discovery, the first assault on an error was the setting up of the individual against the society. The men who first dared to say that the sun did not move round the earth found to their cost what it was to fly in the face of a common, though illusory, perception of the senses.[151] If, however, by common be understood what is permanently and unshakably held true by men in proportion as their minds become enlightened, then science certainly does assume the truth of common perception and belief. Thus, the progress of the physical sciences may be described as a movement towards a new, higher, and more stable consensus of ideas and beliefs. In point of fact, the truths accepted by men of science already form a body of common belief for those who are supposed by all to have the means of testing the value of their convictions. And the same applies to the successive improvements in the conceptions of the moral sciences, for example, history and psychology. Indeed, the very meaning of science appears to be a body of common cognition to which all minds converge in proportion to their capabilities and opportunities of studying the particular subject-matter concerned. Not only so, from a strictly scientific point of view it might seem possible to prove that common cognition, as defined above, must in general be true cognition. I refer here to the now familiar method of the evolutionist.