His face worked as though to speak, but there was an invisible wall between them.

They were sitting apart, as if an invisible wall stood between them.

It was as though invisible walls had been moved off him and miles away.

We have two ventures in one, with an invisible wall.

When the young man got to within five feet of them, he seemed to hit an invisible wall.

And yet between us there is some wall, invisible, still present.

I put my hands against the invisible wall and followed it.

Some invisible wall stopped her hand about a foot from the door.

And there they once more came up against the invisible wall.

An invisible wall stood between him and the woman he loved.