Non omnis tristitia omni delectationi contrariatur quia tristitia et delectatio, cum sint passiones, specificantur ex obiectis.
Not every sadness is contrary to every pleasure because sadness and pleasure, being passions, are specified by their objects.
Et quidem secundum genus suum, contrarietatem habent, nam unum pertinet ad prosecutionem, aliud vero ad fugam, "quae se habent in appetitu sicut affirmatio et negatio in ratione", ut dicitur in VI Ethic.
According to their respective genera, they are contrary to one another, since one is a kind of "pursuit," the other a kind of "avoidance," which "are to the appetite, what affirmation and denial are to the intellect" (Ethic. vi, 2).
Et ideo tristia et delectatio quae sunt de eodem, habent oppositionem ad invicem secundum speciem. Tristitia vero et delectatio de diversis, si quidem illa diversa non sint opposita, sed disparata, non habent oppositionem ad invicem secundum rationem speciei, sed sunt etiam disparatae; sicut tristari de morte amici, et delectari in contemplatione.
Consequently sadness and pleasure in respect of the same object, are opposite to one another according to species, whereas sadness and pleasure in respect of objects that are not contrary but disparate, are not opposite to one another according to the formal aspect of species, but are also disparate; for instance, sadness at the death of a friend, and pleasure in contemplation [of his life].
Si vero illa diversa sint contraria, tunc delectatio et tristitia non solum non habent contrarietatem secundum rationem speciei, sed etiam habent convenientiam et affinitatem: sicut gaudere de bono et tristari de malo.
If, however, those diverse objects be contrary to one another, then pleasure and sadness are not only contrary according to the formal aspect of species, but they also have a certain [mutual] conformity and affinity: for instance to rejoice in good and to be sad about evil.
Etsi non omnis tristitia contrarietur omni delectationi secundum speciem, tamen quantum ad effectum contrariantur: nam ex uno confortatur natura animalis, ex alio vero quodammodo molestatur.
Although not every sadness is contrary to every pleasure according to species, yet they are contrary to one another in regard to their effects: since one has the effect of strengthening the animal nature, while the other results in a kind of discomfort.