Answer: Wanderings
Step-by-step explanation:
“Surely they are but the vagaries of mine own imagination."
The most likely meaning of vagaries in the sentence above is “ wanderings”.
The dictionary meaning of vagaries is; “an unexpected and inexplicable change in a situation”.
The dictionary meaning of wandering is; “leisurely, aimless and pointless travel or movement “.
“Wandering” best replaces the word vagaries because one’s imagination can wander and travel leisurely picturing different thoughts and scenarios.
The sentence can be rewritten as;
“Surely they are but the wanderings of mine own imagination."