107. A class need not necessarily consist of more than two
things. If the sun and moon were the only heavenly bodies in the
universe, the word 'heavenly body' would still be a common term, as
indicating the attributes which are possessed alike by each.

108. This being so, it follows that the division of terms into
singular and common is as exhaustive as the preceding ones, since a
singular term is the name of one thing and a common term of more than
one. It is indifferent whether the thing in question be a substance or
an attribute; nor does it matter how complex it may be, so long as it
is regarded by the mind as one.

109. Since every term must thus be either singular or common, the
members of the preceding divisions must find their place under one or
both heads of this one. Subject-terms may plainly fall under either
head of singular or common: but attributives are essentially common
terms. Such names as 'green,' 'gentle,' 'incongruous' are applicable,
strictly in the same sense, to all the things which possess the
attributes which they imply.

110. Are abstract terms then, it may be asked, singular or common?
To this question we reply--That depends upon how they are used. The
term 'virtue,' for instance, in one sense, namely, as signifying moral
excellence in general, without distinction of kind, is strictly a
singular term, as being the name of one attribute: but as applied to
different varieties of moral excellence--justice, generosity,
gentleness and so on--it is a common term, as being a name which is
applicable, in the same sense, to a class of attributes. Similarly the
term 'colour,' in a certain sense, signifies one unvarying attribute
possessed by bodies, namely, the power of affecting the eye, and in