Another Visual Test
In the same manner your mind can reproduce an unlimited number of pictures. Anything which you have once seen with the physical eye can be reproduced again in the mind's eye.
Make a few tests of this fact, if it is not well known to you. For example,—
See a pasture with a creek flowing through, willows hanging over the water, the green grass on the banks, and the stock grazing there. See several different kinds and sizes of animals, note their color, what they are doing. Add to the detail of the picture.
To close the eyes and thus to eliminate the more distinct impressions of the physical eye, will assist you in visualizing any picture.