It is easier for a camel to pass through the eye of a needle, than for a theologian to enter into the kingdom of heaven.

Bl. John Henry Newman to W.G. Ward, November 8th, 1860:

 I will say as to the very matter which occasions your letter: […]

‘(9) that, as the rich man or the man in authority has his serious difficulties in going to heaven, so also has the learned.

‘(10) that the more a man is educated, whether in theology or secular science, the holier he needs to be if he would be saved.

‘(11) that devotion and self-rule are worth all the intellectual cultivation in the world.

‘(12) that in the case of most men literature and science and the habits they create, so far from ensuring these highest of gifts, indispose the mind towards their acquisition.

The whole letter is quite interesting. Part of it was recently posted by Thomas Cordatus.