THE correspondence on this subject provides a most enlightening example of the present transition in scientific philosophy from the view that science is a description of an objective external world to the view that it is a formulation of the relations found between experiences. Thus, to Sir James Jeans1, taking the older view, light is an objective entity the velocity of which is either finite or infinite, while Sir Arthur Eddington is interested only in the fact that, since our experiences could be correlated equally well or ill by postulating an infinite or an immeasurably large finite velocity, the possibility of the former can be ignored. It is not surprising that, as Sir James rightly complains, Sir Arthur has not answered his objections. They are meaningless in Sir Arthur's philosophy, and he cannot reply in applicable terms.