This is another of the John Silence tall-tales, this time involving a man who learns to visualize 4-dimensional space and then starts slipping in and out of the hyperspace. As he describes it,
"This room we now sit in, Dr. Silence, has one side open to space--to higher space. A closed box only seems closed. There is a way in and out of a soap bubble without breaking the skin."
“Certain people, certain human atmospheres, certain wandering forces, thoughts, desires even--the radiations of certain combinations of colour, and above all, the vibrations of certain kinds of music, will suddenly throw me into a state of what I can only describe as an intense and terrific inner vibration--and behold I am off! Off in the direction at right angles to all our known directions! Off in the direction the cube takes when it begins to trace the outlines of the new figure, the tessaract! Off into my breathless and semi-divine higher space! Off, inside myself, into the world of four dimensions!"