The luminiferous ether is supposed by modern science to be matter in a most refined state. It is the vibrations of this element that are said to constitute light. The vibrations are said to take place at right angles to the direction of the wave. Nearly the same is the description of the Tejas Tattva given in the book. It makes this Tattva move in an upward dirce tion, and the centre of the direction is, of course, the direction of the wave. Besides, it says that one whole vibration of this element makes the figure of a triangle.