Yeats, Georgie - A Vision - The cones and the diamond
Type of Spiritual Experience
In ‘the Vision’, the nature of the Higher spirit and the soul are explained by using both a diamond and a double cone. The Diamond is the Higher spirit, whereas the double cone represents the soul cone with its personality and the body during life [bottom cone] and then the state after death [upper cone].
I'm not entirely sure the summary from the official Internet site for the Vision is much help, but I have included it anyway, as it is at least some background.
A description of the experience
Summary from Internet site
In A Vision this form of representation is most important in the discussion of the Principles, the spiritual constituents of the human being, which come to the fore in the after-life. In this system the axes of the two shapes do not necessarily coincide, and they rotate about a common centre, within a sphere. The Diamond itself represents the original Principle of the Celestial Body, within which the Spirit moves as a single gyre. These together form the Solar element of the system of the Principles, while the Hourglass represents the Lunar element. Both the Passionate Body and the Husk move within this double gyre, one half representing life and the other half the after-life (see the Principles and the After-life).