But the germ in his mind of compassionate protection and instinctive desire to help Fay had in it the possibility of growth, of some expansion.

And what other feeling in Wentworth's clean, well-regulated, sterilized mind had shown any power of growth?
The worst of growth is that a small acorn does not grow into a large acorn as logical persons expect.

It ought to, but it does not.

It grows instead into something quite unrecognisable from its small beginnings, something for which, perhaps, beyond a certain stage, there is no room,--not even a manger.
Those who love must discard much.

Wentworth had not yet felt the need of discarding anything, and he had not the smallest intention of doing so.
He intended instead to make a small ornamental addition, a sort of portico, to his life.