 There are two main puzzles about the Nyāya-Vaiśeṣika theory of composition. First, why can’t two atoms of different types form a dyad? An answer is, if an earth atom and a water atom combine to produce a dyad, to which type will the resultant belong? It cannot belong to both types possessing two exclusive class-characters, nor can the resultant be of a mixed type, for then we shall never have any natural kind of perceptible dimension. The second issue here is why three atoms or two dyads cannot directly produce a composite object. According to the Nyāya-Vaiśeṣikas, sticking to the order of conjunction of atoms is important to explain how perceptible magnitude arises at the stage of triad from the combination of its imperceptible components. If an atom is of imperceptible magnitude, so will be the magnitude of a dyad, for a quality of a part produces in the whole the same quality in greater degree. Now if the dyads are imperceptible, then by the same logic a triad will also be imperceptible. If this process continues, then there will never be any composite object of perceptible dimension. So the Nyāya-Vaiśeṣikas need to give a rational justification for the perceptibility of a triad. They uphold that, unlike other qualities, the magnitude of a compound is not caused by the magnitude of its components. The gross magnitude of a composite whole is a resultant either of the grossness of its component or the looseness of their conjunction or of the plurality of their numbers. The first alternative has already been rejected. The second alternative also is not acceptable to the Nyāya-Vaiśeṣikas because they do not admit any interstice between two atoms. So they endorse the last alternative that the perceptible magnitude of a triad is caused by its number. Some think that triads of different elements can combine to form tetrads, and so on. Since the atoms of different elements have specific qualities, there would be different structural arrangements (vyūha) in triads constituted by different types of atoms. Different qualities observed in large composite substances are due to such different structural arrangements of their components.