He never took his eye off the Public.

He laid his finger, as it were, on that mighty pulse and recorded its fluctuations in his ledger.
But there was a region beyond those fluctuations.

With new books there was always a pound's worth of risk to a pennyworth of profit; but there was no end of money to be got out of old ones, if only you knew how to set about it.

And Isaac did not quite know how.

In his front shop it was the Public, in his side shop it was the books that mattered, and knowledge of the one, however exhaustive, was no guide to the other.