 The second question concerning space involved the possible existence of interstitial voids and focused on whether two atoms could be separated from one another without a third atom’s existing between them. Dhanani (Dhanani 1994, 74–81) has classified the arguments against such a possibility into two types: those involving non-being and those involving the principle ‘nature abhors a void.’ An example of the first kind of argument is the following. Assume that two atoms are separated and that purportedly nothing exists between them. Since one cannot perceive what does not exist, then in the present case one should not be able to perceive a truly empty space between the separated atoms; however, it seems evident that one would be able to perceive the space between them and so that space could not be truly empty, but must be occupied by an atom. An example of the second sort of argument against interstitial voids is taken from the medical arts and the use of cupping glasses for blood letting. It is observed that when a cupping glass is placed over a vein and the air is withdrawn, the flesh is drawn up into the cup. The detractors of interstitial voids used this phenomenon as a verification of the principle that nature abhors a vacuum. Consequently, since nature does abhor a vacuum, void spaces will not exist in nature. Interestingly, the proponents of interstitial voids were able to turn the cupping glass phenomenon against their opponents to show that a void must exist. They had one imagine that a sheet of atoms one atom thick is placed between two cupping glasses and then the air is simultaneously removed from both glasses. Either the sheet is drawn into one or the other glass or it is not. If the sheet is drawn into one cupping glass, there is a void in the other; if the sheet is not drawn into one or the other cupping glass, then there is a void in both. In either case a void has been produced.