It is nearly impossible to understand and appreciate Milton's Il Penseroso without also having read its companion piece, L'Allegro. In 1991 Casey Finch and Peter Bowen wrote that the poems are "unavoidably locked in a condition of textual self-consciousness where, no matter how hard each tries to extricate itself from the embrace of the other, neither can stop thinking and dreaming about its companion" (5).
Many critics have speculated that Milton prefers the pensive melancholy celebrated in Il Penseroso because it represents the ascetic life of study, as opposed to L'Allegro's emphasis on a dionysian, pleasure-seeking lifestyle. Milton appears to make this preference explicit in his sixth Elegy, written to Charles Diodati, when he tells his friend that Apollo, "Bacchus, Ceres, and Venus all approve" of "light Elegy" and assist poets in such compositions, but poets whose ambitions reach higher to the epic and heroic modes must eschew the dionysiac lifestyle for a more ascetic practice:
But they who Demigods and Heroes praise
And feats perform'd in Jove's more youthful days,
Who now the counsels of high heav'n explore,
Now shades, that echo the Cerberean roar,
Simply let these, like him of Samos live
Let herbs to them a bloodless banquet give;
In beechen goblets let their bev'rage shine,
Cool from the chrystal spring, their sober wine!
Their youth should pass, in innocence, secure
From stain licentious, and in manners pure,
Pure as the priest's, when robed in white he stands
The fresh lustration ready in his hands. ("Elegy 6" 55-66)
The poet who seeks to attain the highest level of creative expression must embrace the divine, which can only be accomplished by following the path set out in Il Penseroso. In 1971, David Miller described this concept of the latter poem's superiority to its companion: "The delights of L'Allegro are real and valued, but like the glories of Greece they cannot stand against the ecstasy of Christian contemplation. Partial truth is inferior to complete truth. It is Il Penseroso who represents the proper Christian pattern" (7).
Milton's invocation of the goddess Melancholy reminds one of his salutation to Mirth in L'Allegro, and sets up the parallel structure of the two poems. It also suggests a very specific body of sources, such as Robert Burton's comprehensive Anatomy of Melancholy, John Fletcher's song "Melancholy," and Shakespeare's Hamlet 2.2.309. The concept of "melancholia," however, has its origins in ancient Greece with Hippocrates and his "humours theory" of the body, which was later revised by Aristotle and Galen. Lawrence Babb discovered two forms of melancholy in his study of Il Penseroso: "black" and "golden tinged with purple." While black melancholy was responsible for severe depression, the Aristotlian gold melancholy "was the concern, not of physicians, but of poets. And its products were not despondency amid madness, but the highest of man's artistic achievements" (Miller 32). Milton's choice of "Penseroso" in the title, over "Melancolico" or "Afflitto," indicates his emphasis on the positive and spiritual aspects of Melancholy (Hughes, Variorum 237).
In her book The Gendering of Melancholia, Juliana Schiesari writes that "the very nature of the melancholic was to be that of a self split against itself" (8). It is significant, then, that Il Penseroso has a companion. While some critics argue that the two poems refer equally to Milton (Hughes, Variorum 245), others believe that L'Allegro was about his friend, Charles Diodati, while Il Penseroso was autobiographical in nature. If this was the case, then Milton may have consciously adopted part of Spenser's theory of friendship in writing the poem — namely, the idea that friends "express different aspects of the same principle, [as] shown by the frequent citing of one of them to prove the other" (Smith 43). Il Penseroso's initial banishment of Mirth — as well as L'Allegro's exile of Melancholy — demonstrates this principle at work.
The copytext for this edition of Il Penseroso is a copy of Milton's 1645 Poems owned by Rauner Library at Dartmouth College (Hickmot 172).