But you realise, when you have been in that country for a little while, that you have eyes upon you all the time—­you are being watched as you have never been watched in your life before.  You move along the country road as you would walk along the roads about your own home, until, sooner or later, things happen which make you think suddenly and think hard.  You are passing, a dozen of you together instead of the usual two or three, through those green fields by those green hedgerows when there is a sharp whiz and a crash, and a shrapnel shell from a German seventy-seven (their field gun) bursts ten yards behind you.  You are standing at a corner studying a map, and you notice that a working party is passing the corner frequently on some duty or another.  You were barely aware that there was a house near you.

Twenty-four hours later you hear that that house was levelled to the ground next morning—­a shrapnel shell on each side of it to get the range—­a high explosive into it to burst it up—­and an incendiary shell to burn the rubbish; and one more French family is homeless.

It takes you some time to realise that it was you who burnt that house—­you and that working party which moved past the cross-roads so often.  Somebody must have seen you when the shell burst alongside that hedge.  Somebody must have been watching you all the time when you were loitering with your map at that corner.  Somebody, at any rate, must have been marking down from the distance everything that happened at those cross-roads.  Somebody in the landscape is clearly watching you all the while.  And then for the first time you recall that those grey trees in the distance must be behind the German lines; that distant roof and chimney notched against a background of scrub is in German ground; the pretty blue hill against which the willows in the plain show out like a row of railway sleepers is cut off from you by a barrier deeper than the Atlantic—­the German trenches; and that from all yonder landscape, which moves behind the screen of nearer trees as you walk, eyes are watching for you all day long; telescopes are glaring at you; brains behind the telescopes are patiently reconstructing, from every movement in our roads or on our fields, the method of our life, studying us as a naturalist watches his ants under a glass case.

Long before you get near the lines, away over the horizon before you, there is floating what looks most like a flat white garden grub—­small because of its distance.  Look to the south and to the north and you will see at wide intervals others, one after the other until they fade into the distance.  Every fine day brings them out as regularly as the worms rise after rain; they sit there all day long in the sky, each one apparently drowsing over his own stretch of country.  But they are anything but drowsy.  Each one contains his own quick eyes, keen brain, his telescope, his telephone, and heaven knows what instruments.  And out on every beautiful fresh morning of spring come the butterflies of modern warfare—­two or three of our own planes, low down; and then a white insect very, very high—­now hidden behind a cloud, now appearing again across the rift.  It is delightful to stand there and watch it all like a play.  The bombs, if they drop ’em, are worth risking any day.