Avatar, first published in 1856, is a Fantastique novella by French writer Théophile Gautier.
Octave's friends and relatives, who fail to understand the source of his illness, resort to a peculiar and rather mysterious physician who spent several years in India leading an ascetic life.
The physician, Balthazar Cherbonneau, offers to swap Octave's mind with Olaf's using magic he learned in India.
Cherbonneau tricks Olaf while he is visiting and successfully switches Octave's and the count's minds.
Unwilling to harm their original bodies, the two men agree to go to Cherbonneau and fix the exchange.