Aristotle has just finished discussing how privations may show a difference in meaning. He continues his explanation of the second tool by showing that related words can also show a difference in meaning. He does this in Topics, Book 1.
Moreover, examine the inflected forms. For if ‘justly’ is used in more than one way, the ‘just’, also, will be used in more than one way; for there will be a ‘just’ corresponding to each ‘justly’; e.g. if ‘justly’ is used of judging according to one’s own opinion, and also of judging as one ought, then ‘just’ also will be used in like manner. In the same way also, if ‘healthy’ is used in more than one way, then ‘healthily’ also will be used in more than one way: e.g. if healthy is what produces health and what preserves health and what betokens health, then ‘healthily’ also will be used to mean ‘in such a way as to produce’ or ‘preserve’ or ‘betoken’ health. Likewise also in other cases, whenever the original term is used in more than one way, the inflexion also that is formed from it will be used in more than one way, and vice versa.
We should also examine related words. In Greek these related words are indicated by inflected forms, but in English we do not necessarily do that. Consider the word ‘just’. In English, this word is related to the word ‘justly’. If either of these is used in multiple ways, then they are both used in multiple ways. This also applies to the word ‘healthy’. We speak of ‘healthy’ and ‘healthiness’. If these all refer to the same thing, then they will all have the same meanings. They would all mean to preserve, produce or indicate health. This applies to all related words.
Next, Aristotle discusses how predicates can show a difference in meaning.