This phrase should be clearly understood.

It meant if there was any one thing that he _did_.
For instance if he had only _collected_ anything.

Thus, there was Mr.
Lucullus Fyshe, who made soda-water, but at the same time everybody knew that he had the best collection of broken Italian furniture on the continent; there wasn't a sound piece among the lot.
And there was the similar example of old Mr.Feathertop.He didn't exactly _collect_ things; he repudiated the name.

He was wont to say, "Don't call me a collector, I'm _not_.

I simply pick things up.