Zanoni by BULWER-LYTTON, Edward

Zanoni, a timeless Rosicrucian brother, cannot fall in love without losing his power of immortality; but he does fall in love with Viola Pisani, a promising young opera singer from Naples, the daughter of Pisani, a misunderstood Italian violinist. An English gentleman named Glyndon loves Viola as well, but is indecisive about proposing marriage, and then renounces his love in order to pursue occult study. The story develops in the days of the French Revolution in 1789. Zanoni has lived since the Chaldean civilization. His master Mejnor warns him against a love affair but Zanoni does not heed. He finally marries Viola and they have a child. As Zanoni experiences an increase in humanity, he begins to lose his gift of immortality.( Summary by Wikipedia )