Ascending the stairs
Beckford uses a metaphor to describe Vathek's excessive pride, by saying that "his pride arrived at its height when, having ascended for the first time the eleven thousand stairs of his tower, he cast below." Here, his ascent up the stairs is a metaphorical representation of his self-importance.
The return of the fifty children
The resurrection of the fifty sacrificed children at the end of the text is a metaphor for the restoration of moral order. The return of the fifty children represents the return of hope and moral goodness back into the world.
Vathek's demise
Vathek's demise is a metaphor for the downfall of an immoral person, and what happens to someone when they engage with transgressive or immoral behavior. As such, the whole text functions as a warning against following an unethical way of life.
Sight vs. Light
Beckford uses a metaphor in the following passage:
"He consoled himself, however, for this transient perception of his littleness... and flattered himself that the light of his mind would extend beyond the reach of his sight, and transfer to the stars the decrees of his destiny."
This metaphor is used to describe how his true fate is beyond the understanding of the present moment but will be revealed with time.
Vathek's tower
Vathek's tower is a metaphor for his greed and pride. Although his money would be better spent on improving his kingdom and the lives of his subjects, he instead directs his resources to the building of an excessive tower.