Berkeley is most importantly a philosopher, the second of the three British Empiricists, following John Locke and preceding David Hume. AN ESSAY TOWARDS A NEW THEORY OF VISION was published in 1709, one year before his first important philosophical work, A TREATISE CONCERNING THE PRINCIPLES OF HUMAN KNOWLEDGE. Yet the ESSAY is not primarily a philosophical work. It is a study of visual perception which is best classed with experimental psychology. Its major objective is to show how we perceive the distance and size of objects and their spatial relation to other objects. In so doing, Berkeley manages to criticize most of the accepted views on the topic. The last part of the ESSAY is a consideration of the difference between perception by sight and by touch and of whether we ever perceive the same thing by both faculties. It is in his treatment of this latter issue that Berkeley hints at the philosophical doctrines which he soon elaborated.