Enjoying things which are pleasant; that is not the evil: it is the reducing of our moral self to slavery by them that is.

Thomas Carlyle (1795-1881) Scottish essayist and historian

Lecture (1840-05-08), “The Hero as Prophet,” Home House, Portman Square, London
    (Source)

The lecture notes were collected by Carlyle into On Heroes, Hero-Worship, & the Heroic in History, Lecture 2 (1841).