adverse

That is to say, if Reason is proved to control the passions adverse to temperance, gluttony and lust, it is also clearly shown to be lord over the passions, like malevolence, opposed to justice, and over those opposed to manliness, namely rage and pain and fear.

The answer is that Reason is not master over defects inhering in the mind itself, but over the passions or moral defects that are adverse to justice and manliness and temperance and judgement; and its action in their case is not to extirpate the passions, but to enable us to resist them successfully.