From being brisk and bright, he now became, most unaccountably, a slow, solemn, and pondering young man.
"This question has two sides," he said.

"An Objective side, and a Subjective side.

Which are we to take ?" He had had a German education as well as a French.

One of the two had been in undisturbed possession of him (as I supposed) up to this time.
And now (as well as I could make out) the other was taking its place.

It is one of my rules in life, never to notice what I don't understand.