There are two things you have to look out for, two extremes:
On the one hand, an impractical realism,
and on the other hand, a sort of passive realism.
The impractical idealism is the kind that says, 
“I’ve worked it out beforehand, and that’s the way it’s got to be.”

Both these views are basically static.  They never get anywhere.
In between, there is a wholistic view, which is:

“In the reality which I have and am now, there is a possibility for 
growth which God has put there.  There’s a seed God has planted
there and is going to make grow, and what I have to provide is 
the love and assent that’s going to permit it to grow.”

On the other hand, the passive kind of realism says,
“Well, this is the way it is, what can I do?”
And just does nothing.

—Thomas Merton