3 And the hidden treasures in her sacred tomb 4 With sacrilege to dig. Therein he found 5 Fountains of gold and silver to abound,

Fountains > Founts, sources

6 Of which the matter of his huge desire

matter > substance

7 And pompous pride eftsoons he did compound;

eftsoons > soon compound > {Compose, make up with the combination of elements (i.e. gold and silver)}

8 Then avarice gan through his veins inspire

gan > did inspire > breathe life, quicken

9 His greedy flames, and kindled life-devouring fire."

His > [Those of avarice; or: those of man]