This paper is concerned with an examination of canti iv through viii of Book II of The Faerie Queene, with especial attention paid to the events in the Cave of Mammon, and with the Middle English poem Sir Gawayn and the Grene Knyzt. It is suggested in this paper that Spenser may have been aware of Sir Gawayn, and that consideration of that possibility can result in a more coherent reading of the central section of The Faerie Queene. Studies of Book II of The Faerie Queene have revealed that Spenser made liberal use of source materials in his composition, many of which have been identified, with the notable exception of what exists as canti iv through viii. Although parallels have been suggested for individual items in that section, no such suggestions have been made for the overall temptation complex itself. It seems possible that the events in that complex are unified by a use of the temptation motif as found in Sir Gawayn and the Grene Knyzt, rearranged and altered to suit the demands of an allegory about a figure of Temperance. When this possibility is examined, it reveals that the visit of Guyon to the Cave of Mammon is not at all a digression, nor are the battles with Pyrochies and Cymochles disconnected from the plot in an allegorical reading; rather, the events form a thematic and imagistic whole. If this is the case, then this central section of Book II would depict Guyon engaged first in battles with excesses of activity and indolence, in both of which battles Guyon triumphs; then, by entering into the Cave of Mammon, Guyon fails in temperance. Although he was superior to external excesses he was prey to his own intemperate reliance upon himself and serving of his intellectual curiosity at the expense of his physical needs. In the Cave, Mammon tempts Guyon first with excess of overactivity and with excess of indolence, which excesses Guyon overcomes; then, in the Garden of Proserpina Guyon is tempted with an explicit extension of the failing he demonstrated by entering the Cave. Although he succeeds in resisting in that latter case, he is punished for the initial failing by his faint upon emerging from the Cave. This might have been suggested by Gawain's temptations and single, partial failing in Sir Gawayn and the Grene Knyzt. It is possible that Spenser did indeed encounter Sir Gawayn, for the copy British Museum Cotton MS Nero A. X. was obtained from the library of Sir Henry Savila, who was tutor to the Queen at the same time as Spenser was in the employ of Leicester, the Queen's favorite. Although there are no verbal parallels between the two poems, there are suggestions of possible parallels in image and idea beyond the most significant suggestion of reversed-order parallel of structure. The value of an examination of source lies in the light which the examination sheds upon the text, and the most telling support for this theory which can be offered is the expansion of the text provided by this reading.