The Allegorical Shrines in Spenser's Legend of Justice. Added to this, Stump connects the lions that appear in both scenes to further prove his point.
Stump proceeds to give an historical reading to justify the existence of two houses of instruction.
Stump proves his argument very convincingly, and his close reading of the text helps to understand the complex allegories going on in these passages. However, rather than reading Mercilla's mercy as a superior virtue to Isis's equity, I think that one could also read the episode of Isis church as a description of the virtues that Mercilla, as the paradigm of justice, displays. That is, I do not think that these two figures should be read in opposition to each other, but I am inclined to see Isis and Osyris as the components of Mercilla's perfect justice.