It is therefore obvious that Dr. Whitehead’s criticism, when interpreted as referring to psychological simultaneity, appears to be totally unwarranted. Let us see whether it would possess any greater merit when interpreted as referring to a simultaneity of external events. The criticism would then have the following significance: Our recognition of the simultaneity of external events is fundamental. We know that two events, one on the sun and the other on the earth, are simultaneous, when we perceive them simultaneously. Physical measurements are irrelevant to the problem. Einstein’s theory fails to recognise this fact. Now there is no doubt that the theory of relativity does fail to recognise the type of simultaneity presented in this last interpretation of Dr. Whitehead’s criticism. Hence the man who might have this understanding in mind would be perfectly justified in dissenting from a theory which would characterise his conception of simultaneity as altogether indefensible. But, for that matter, so would classical science. Both sciences refuse to agree that we possess any a priori means of determining a simultaneity of external events. Both sciences claim that in all such cases we are compelled to appeal to physical measurements of one kind or another. In other words, both sciences refuse to accept that bizarre doctrine known as “neo-realism” which consists in confusing the event that, occurs with the event that we sense. [Pg 175] According to neo-realism as championed by Whitehead, and by a number of other philosophers, vision is a matter of direct apprehension[57] Events would thus be simultaneous with the instants of their perception. In the same spirit, the neo-realist speaks of events occurring behind a mirror, or of the space he sees behind the mirror, or of the convergence of the rails on the embankment. No distinction in terminology is made between the status of such perspectives and that of the physical entities existing in the objective world of science. In ancient times Æsop warned his countrymen against the dangers of neo-realism when he composed his fable of the dog mistaking the bone for its reflection in the water. Indeed, for the plain man there appears to be no difference between the attitude of the neo-realist and that of the unsophisticated infant or primitive savage who views a mirror for the first time.