But, when I began the History, I was enchanted, and thought more highly of him than ever.

I went back to the Annals, and liked them even better than the History.

All at once the explanation of this occurred to me.

While I was reading the Annals I was reading Thucydides.

When I began the History, I began the Hellenics.
What made the Annals appear cold and poor to me was the intense interest which Thucydides inspired.