In Dante's Purgatory, there are few items that its reader encounters which match the sheer intensity of image that is conjured up by the poet's three dreams. Almost no other event within the poem reverberates with the sensory experiences that these three sequences do, perhaps because so few are as resistant to a simple, concrete, and rational interpretation. Most structures or motifs in the poem, such as the imprinted P's on Dante's forehead, the various divine guides which lead him across the mountain of Purgatory, the fragments of prayer that he encounters along the course of his journey, the painted mosaics of virtue or of sin posted at the beginning of each cornice, or even the individual sinners and their respective punishments have distinct and immediate allegorical context.

Such is decidedly not the case with the three dreams, and although each of these three have attributes or elements that can be imbued with allegorical significance, each has a larger meaning that is wholly its own and is not easily explained via any single interpretation. What can be said, however, is that each has a unique, if similar, structural significance in the poem, and each is comprised from its own particular language of symbol and metaphor, much like any real dream. For this reason, each of the three, although still connected to the other two dreams in fundamental ways, is its own distinct animal, filled with individual sensory experience that survives beyond mere intellectual understanding precisely because it cannot be fully rationalized.

The first of Dante's three dreams, that image of the Eagle which appears in Canto IX, serves Dante a simple and immediate poetic purpose: as prelude to the entrance into Purgatory proper from Anti-Purgatory. By buffering the events between the lower terraces and those of the upper cornices with this dream, Dante helps to ease the transition between the two quadrants of Purgatory.

The dream itself, however, has several unique attributes that distinguish it beyond mere literary function. It is the only dream of the three which directly reflects the direct physical circumstance of Dante's character in the poem, and the connection between the Eagle which lifts the poet in his dream and the divine Lucy, who is actually carrying Dante while he dreams, is reinforced by such metaphoric details as the divine attributes of the Eagle (line 20), its fixed and determined flight path (lines 25-28), and Dante's allusion to Ganymede (lines 22-24) - a mythical figure who was also raised up by a divine figure. Also, the fact that the dream concludes just at Lucy departs also helps to connect her identity with that of the Eagle. Indeed, as Dorothy Sayers notes in her annotation on this passage, the physical act of transportation that Lucy imparts upon Dante "both induces and fulfils the dream which symbolizes it."

These details and others, however, have additional metaphoric weight that pushes a reader away from just one simple equation between the eagle and Lucy. Descriptions, for instance, of the glory of the elevating creature help to support a possible interpretation of the Eagle as that which it typically signifies in Dante - the glory of the Roman Empire. Also, the very process of this dream - wherein Dante surrenders to a higher intelligence, avoids danger precisely because of this surrender, and passes through a cleansing plane of fire (lines 30-32) - sounds an awful lot like Dante's journey up Purgatory in miniature, and the Eagle can therefore be seen, in the broadest sense, as any one of Dante's particular guides.

Dante's second dream, that of the Siren in Canto XIX, also functions as a bridge between two events within the poem, this time between Dante's exit from both the cornice of sloth and the second evening and his arrival at both the next day and, with it, those cornices, beginning with the covetous, which will be characterized by excessive love. In the same manner that the dream of the Eagle serves as a buffer between two greatly differing locales, so does the Siren dream help to connect the two events that it spans in between.

Yet if the Eagle was symbolic in nature - of Lucy, of the Empire, of Dante's journey - the episode of the Siren is at once both more immediate and much more metaphoric than that previous dream. With the Siren canto, one notices less the broad analogous generalities of Dante' s situation than they do the particular interactions between the poet and the Siren, and for this reason the dream can be interpreted much more literally than its previous counterpart. The fact that the woman that Dante meets is both impotent and ugly (lines 8-9) until Dante's gaze, which is usually passive, actively converts her into a powerful object of beauty (lines 10-15) is significant, because it works to define, in metaphoric terms, the process in which love becomes excessive. Such action demands the creation of a false projection, which the Siren can be seen to represent, on which the creator must hoist his own imagination upon. This, of course, will correspond directly to the spiritual location that Dante and Virgil are at within Purgatory, and via the metaphoric language of this dream, the poet will successfully interact with an exemplar of this excessive love in an indirect manner without actually experiencing it, thus avoiding sin.

Dante's third dream, of Leah and Rachel, is perhaps the most explicitly symbolic of the sequence, and contains elements that are the most directly equitable with abstract concepts. Like the other two dreams, this third also serves to buffer a transition, this time between Dante's passage through the fire of the final cornet and his entrance into the earthly paradise. It is perhaps appropriate that this dream sequence, which is certainly the most abbreviated of the three, can be seen as an introduction into exactly the type of divine thinking that one might enact within Paradise. When Dante meets the two women along with their respective symbolic accessories, he is encountering in physical form twin aspects of the virtuous life; Leah, with her arrangements of flowers, reflects the active portion of life, whereas Rachel, with her perpetual gaze into a mirror, represents the contemplative. The implication is that Dante will have to fully engage both aspects before he can properly enter the earthly paradise.

Superficially, each of these three dreams have many things in common. Each occurs at or immediately around a canto that is a multiple of nine; the first and last dreams are at cantos 9 and 27 respectively, and one suspects that the second would have occurred at 18 if Dante's structure had permitted it. Each, as has been previously mentioned, bridges two important events in the poem, and each contains allusions to antiquity that reinforce - if they do not comprise entirely - themes within the given dream. Each occurs at dawn, the standard time for prophetic dreaming, not because each foretells some specific detail, but because each will be directly and thematically applicable to the spiritual circumstance of Dante at the time of his dream. Finally, each goes to great length, whether it be by rendering Dante burned by fire, overwhelmed by smell, or enchanted by visions, to introduce specific sensual details into the final moments of the dream, perhaps blurring the line between what is imagined and what is actual.

More importantly, however, each of the dreams shares the sense that a large amount of its composition seems to be arbitrary. One cannot, for instance, read Dante's account of his dreams in anything other than an indirect language of metaphor and symbol, and try as one might they cannot fully rationalize away his choice of the Eagle, Siren, Leah or Rachel within each of their respective dreams. This frustration itself, however, seems to also be a realistic detail within Dante's design, for he was surely aware that dreams themselves speak only indirectly to their dreamers, and that a great amount of the intelligence within dream resides in that which moves beyond the ordinary syntax of human understanding. In interpreting dreams, Dante perhaps understood that it was impossible to confine the music of dreams to a single, rigid interpretation, and it is for this reason that his dreams contain one attribute that is realistically dreamlike: they vibrate between many different meanings simultaneously.