καὶ μὴν θεωρητικῆς γε τῆς ψυχῆς οὔσης ἅμα καὶ πρακτικῆς, καὶ θεωρούσης μὲν τὰ καθόλου πραττούσης δὲ τὰ καθ’ ἕκαστα, καὶ νοεῖν μὲν ἐκεῖνα ταῦτα δ’ αἰσθάνεσθαι δοκούσης, ὁ κοινὸς λόγος ἀεὶ περί τε ταὐτὸν ἐντυγχάνων τῷ θατέρῳ καὶ ταὐτῷ περὶ θάτερον ἐπιχειρεῖ μὲν ὅροις καὶ διαιρέσεσι χωρίζειν τὸ ἓν καὶ τὰ πολλὰ καὶ τὸ ἀμερὲς καὶ τὸ μεριστόν, οὐ δύναται δὲ καθαρῶς ἐν οὐδετέρῳ γενέσθαι διὰ τὸ καὶ τὰς ἀρχὰς ἐναλλὰξ ἐμπεπλέχθαι καὶ καταμεμῖχθαι δι’ ἀλλήλων.
Now, as the soul is at once contemplative and practical and contemplates the universals but acts upon the particulars and apparently cognizes the former but perceives the latter, the reason common to both (ὁ κοινὸς λόγος) as it is continually coming upon difference in sameness and upon sameness in difference, tries with definitions and divisions to separate the one and the many, that is the indivisible and the divisible, but cannot arrive at either exclusively, because the very principles have been alternately intertwined and thoroughly intermixed with each other.
(trans. H. Cherniss)
This is clearly a Platonist attempt to make sense of the inter-relation between theoretical understanding and practical reasoning based upon a metaphysical account of the relationship between universals and particulars. (There are also evident Aristotelian influences on this view. Compare, for example: NE 1139a5–15.) What is important for present purposes is that these are most emphatically two related uses of reason.
The second passage is at Virt. mor. 443E, a work with very strong Peripatetic influences, which offers a similar division further identifies the virtue of the theoretical use of reason as wisdom, σοφία, and of the practical use of reason as prudence, φρόνησις.)
ἔστι τοίνυν τῶν πραγμάτων τὰ μὲν ἁπλῶς ἔχοντα τὰ δὲ πῶς ἔχοντα πρὸς ἡμᾶς• ἁπλῶς μὲν οὖν ἔχοντα γῆ οὐρανὸς ἄστρα θάλασσα, πῶς δ’ ἔχοντα πρὸς ἡμᾶς ἀγαθὸν κακόν, αἱρετὸν φευκτόν, ἡδὺ ἀλγεινόν. ἀμφοῖν δὲ τοῦ λόγου θεωρητικοῦ ὄντος τὸ μὲν περὶ τὰ ἁπλῶς ἔχοντα μόνον ἐπιστημονικὸν καὶ θεωρητικόν ἐστι, τὸ δ’ ἐν τοῖς πῶς ἔχουσι πρὸς ἡμᾶς βουλευτικὸν καὶ πρακτικόν• ἀρετὴ δὲ τούτου μὲν ἡ φρόνησις ἐκείνου δ’ ἡ σοφία.
Now in the world things are of two sorts, some of them existing absolutely, others in some relation to us. Things that exist absolutely are earth, heavens, stars, sea; things that exist in relation to us are good and evil, things desirable and avoided, things pleasant and painful. Now reason contemplates both of these but when it is concerned merely with things which exist absolutely, it is called scientific and contemplative; and when it is engaged with those things that exit in relation to us it is called deliberative and practical. The virtue of the latter activity is call prudence and of the former wisdom.
(trans. W. C. Hembold)
This passage is, admittedly, a little odd since it would appear to make a grasp of truths concerning the sea, for example, part of theoretical wisdom whereas thoughts about what is good will belong to practical wisdom only. This is perhaps a sign of a very strong Peripatetic influence here. Nevertheless, the general point is clear that Plutarch is not averse to offering reason differing spheres of activity and tends to discriminate these by different kinds of object.
It would be reasonable to think, given this view, that there could be rational pleasures associated with both the cognition of universals and the learning or perception of particulars and that appears to be the view offered in Non posse.