In sociology alienation is a more complex and difficult idea.

That may be a difficult idea to understand at first.

Thinking about her hands on his naked flesh made it a difficult idea to abandon.

He can only think in too simple words for difficult ideas.

But other difficult ideas were basic to what I wanted to get across.

For some reason, this seemed a difficult idea for him to master.

It is an idea extremely difficult to get into set terms.

Darling, these are big difficult ideas, Dust and so on.

What you seem to be able to do is to visualize extremely difficult ideas in very simple terms.

This is good practice for verbalising more difficult ideas later on.