motive force

They stood paralyzed and only recovered motive force when a neighbour suggested their reading the accompanying letter.

The wave—a billow broken to atoms, yet still retaining all its weight and motive force—overwhelmed the boat and passed on.

As for the will, the best authorities hold that it is almost if not entirely dependent upon desire for its motive force.

In his discussion on growth it is interesting to find the idea of turgescence supplying the motive force for extension.

The motive force of his career was however his love of scientific work for its own sake.