meditatio at the water's edge

I was rereading parts of Thomas Merton's "Thoughts in Solitude" this past week, and one little paragraph really keeps bothering me. It reads:
"There is no hope for the man who struggles to obtain a virtue in the abstract--a quality of which he has no experience. He will never efficaciously prefer the virtue to the opposite vice, no matter how much he may seem to despise the latter."

Yes, an irritating little quote. I hope it produces a pearl.