Passions, remember, are not necessarily aligned with reason.
Passions are responses to sensory objects.
I desire an orange solely because I see the orange. I then judge with reason whether or not it is good to have the orange. But, the virtues temperance and fortitude deal with putting reason into passions. Say that the orange I mentioned above does not belong to me, but that I have an overwhelming desire to take it anyway. Temperance is the virtue that interferes with that desire and points out that taking the orange would be against reason.