The Rationalist — Warwick Collins

Silas Grange is a handsome young doctor who prides himself on keeping his appetites under perfect control. But when Grange is summoned by a mysterious, voluptuous widow named Celia Quill, he submits readily to the power of her sensuality. Calmly, expertly, and with studied poise, Mrs. Quill initiates Grange into pleasures beyond his imagination . . . and then proceeds to betray him with deceit beyond his darkest fears.
Set in an eighteenth-century English world of polished surfaces and secret desires, THE RATIONALIST weaves a story of reason overthrown by passion, pure intellect subverted by sexual obsession. Warwick Collins, acclaimed author of CHALLENGE, proves himself a master of historical fiction and a prose stylist of extraordinary power.
"Ironic and deliciously lustful . . . THE RATIONALIST is classically elegant and romantically sensuous, comic and sexy." -- New York Newsday