The core idea of Comus is the high dedication required for those embarked on the philosophical quest for a higher understanding of truth and beauty as understood by the Renaissance and Reformation Platonists. That is, arguably, the broad philosophical setting. Platonic themes resonate throughout the play beginning immediately with the descent of the attendant Spirit from the eternal realm into this lower, lesser world mirroring the Platonic descent of the preexistent soul from the eternal realm to earth. Likewise, the ascension of the Spirit at the end of the play represents the return of the preexistent soul to its source.

On a personal level, Milton may have been using "Comus" as a vehicle to express a rational and natural defense of the virtue, temperance, and even chastity he believed was necessary for any man in general, and himself in particular, to reach a higher moral and intellectual level. Biographically, Milton wished to continue his complete devotion to his studies at Horton as he already planned to become a great man and knew that reaching his goal would require his complete dedication. Milton apparently felt he needed to explain and justify this unusual degree of devotion on philosophical grounds to those friends and family members that were expecting him to give up his cloistered academic life, get married and join the vita activa.

Chastity was, consequently, not an end in itself for Milton but represented, in this case, the type of sacrifice and single-minded dedication he believed was necessary for him to achieve his goal of moving to a higher level of understanding. Virtue in Comus also makes the most sense when understood in the Platonic manner. Milton through the masque states that heaven itself will intercede when necessary to defend the virtue of a pure soul with "just hands" in order to guide such men to rise upward on earth. This is yet another Platonic doctrine present in Comus.

Yet some there be that by due steps aspire

To lay their just hands on that Golden Key

That ope's the Palace of Eternity:

To such my errand is, and but for such,

I would not soil these pure Ambrosial weeds,

With the rank vapours of this sin-worn mould.