An unknown reader is afraid that I be uplifted by the anonymous admiration of one man and sends me the following warning :
Youth unadmonished by a guide
Will trust to any fair outside
An error soon corrected
For who but learns by riper years
That man when smoothest he appears
Is most to be suspected.
These lines are so familiar that I ought to know whose they are and where to find them and yet I do not.
(Some quick research suggests this might be a variation of a William Cowper poem “On Friendship“)