a spirit of good
The context strongly suggests that it is the ever-watchful Creature who is
sustaining Victor's life throughout his long voyage, not the
heaven-directed spirits that Victor imagines. Thus, this phrase is
heavily weighted with irony. The irony is in fact attenuated, for Mary
Shelley could not have written this phrase without consciousness of
P.B.
Shelley's title, "Alastor, or the
Spirit of Solitude," the poem he published in 1816, three months before the
excursion to Lake Geneva. An
alastor in Greek is an evil spirit.