Hamlet, sometime Prince of Denmark, warned his friend that there were more things in heaven and earth than dreamed of in his philosophy. Now, both Hamlet and Horatio had absorbed the contemporary wisdom of Wittenberg. And let it be said in passing that their knowledge did not lag behind ours, metaphysically speaking. Nevertheless, Hamlet, if he had lived longer, might have said that no philosophy would ever solve the riddle of the sphinx; that we never know, only name, things. Noah is the supreme symbol of science, he the first namer of the animals in the ark. The world of sensation is our ark and we are one branch of the animal family. We come whence we know not and go where we shall never guess. Standing on this tiny Isle of Error we call the present, we think backward and live forward. Hamlet the sceptical would now demand something more tangible than the Grand Perhaps. My kingdom for a fulcrum! he might cry to Horatio--on which I may rest my lever and pry this too too solid earth up to the starry skies! What the implement? Religion? Remember Hamlet was a Catholic, too sensitive to send unshrived to hell's fire the soul of his uncle. Philosophy? Read Jules Laforgue's Hamlet and realise that if he were alive to-day the melancholy Prince might be a delicate scoffer at all fables. A Hamlet who had read Schopenhauer. What then the escape? We all need more elbow-room in the infinite. The answer is--the Fourth Dimension in Higher Space. Eureka! After studying Saint Teresa, John of the Cross, Saint Ignatius, or the selections in Vaughan's Hours with the Mystics, even the doubting Thomas is forced to admit that here is no trace of rambling discourse, fugitive ideation, half-stammered enigmas; on the contrary, the true mystic abhors the cloudy, and his vision pierces with crystalline clearness the veil of the visible world. As literary style we find sharp contours and affirmations. Mysticism is not all cobweb lace and opal fire. Remember that we are not stressing the validity of either the vision or its consequent judgments; we only wish to emphasise the absence of muddy thinking in these writings. This quality of precision, allied to an eloquent, persuasive style, we encounter in Claude Bragdon's Four Dimensional Vistas. The author is an architect and has written much of his art and of projective ornament. (He was a Scammon lecturer at the Chicago Art Institute in 1915.) He is a mystic. He is also eminently practical. His contribution to æsthetics in The Beautiful Necessity is suggestive, and on the purely technical side valuable. But Mr. Bragdon, being both a mathematician and a poet, does not stop at three-dimensional existence. Like the profound English mystic William Blake, he could ask: "How do you know but every bird that cuts the airy way is an immense world of delight, closed by your senses five?"