"We just can’t tell what they will do when they stop grinning"

Quoted out of context, for good use of short sentences -- Michael Wood in his essay on Yeats and violence (he is writing about this):

The soldiers are cold and tired and complaining. They have lost hope and they have blood-stained hands: they are soldiers. They die, and they tell us about dying. Then all at once they are grinning and saved. Well, they have arrived in paradise. No, in our paradise, the paradise of right or left, the saved bourgeois world or the new order after the revolution, neither of which would be glad to see the dirty soldiers of the earlier conflict again. That’s why the soldiers are grinning. They know how upset we are to see them. And they seem at the end to know who they are. They are not the drunken soldiery of ‘Nineteen Hundred and Nineteen’, but they are violent dead men who won’t die, who have been through several secular hells, and their grins promise all kinds of havoc in the place we thought was perfect. They are not ‘the worst rogues and rascals’; they are not even ‘weasels fighting in a hole’. They have been fighting in a hole, but they are not weasels. But they are anarchic enough, convincing enough, lively enough, to end any dream of order. We just can’t tell what they will do when they stop grinning.

Elsewhere in the piece, there is much to like, most valuably (for me) this Yeats poem, which I'd forgotten:

The Magi

Now as at all times I can see in the mind’s eye,
In their stiff, painted clothes, the pale unsatisfied ones
Appear and disappear in the blue depth of the sky
With all their ancient faces like rain-beaten stones,
And all their helms of silver hovering side by side,
And all their eyes still fixed, hoping to find once more,
Being by Calvary’s turbulence unsatisfied,
The uncontrollable mystery on the bestial floor.