The doctor had not realized before the boldness and liveliness of his companion’s mind.  Sir Richmond insisted that the climate must have been moister and milder in those days; he covered all the downlands with woods, as Savernake was still covered; beneath the trees he restored a thicker, richer soil.  These people must have done an enormous lot with wood.  This use of stones here was a freak.  It was the very strangeness of stones here that had made them into sacred things.  One thought too much of the stones of the Stone Age.  Who would carve these lumps of quartzite when one could carve good oak?  Or beech—­a most carvable wood.  Especially when one’s sharpest chisel was a flint.  “It’s wood we ought to look for,” said Sir Richmond.  “Wood and fibre.”  He declared that these people had their tools of wood, their homes of wood, their gods and perhaps their records of wood.  “A peat bog here, even a few feet of clay, might have pickled some precious memoranda....  No such luck....  Now in Glastonbury marshes one found the life of the early iron age—­half way to our own times—­quite beautifully pickled.”

Though they wrestled mightily with the problem, neither Sir Richmond nor the doctor could throw a gleam of light upon the riddle why the ditch was inside and not outside the great wall.

“And what was our Mind like in those days?” said Sir Richmond.  “That, I suppose, is what interests you.  A vivid childish mind, I guess, with not a suspicion as yet that it was Man ruling his Planet or anything of that sort.”

The doctor pursed his lips.  “None,” he delivered judicially.  “If one were able to recall one’s childhood—­at the age of about twelve or thirteen—­when the artistic impulse so often goes into abeyance and one begins to think in a troubled, monstrous way about God and Hell, one might get something like the mind of this place.”

“Thirteen.  You put them at that already?...  These people, you think, were religious?”

“Intensely.  In that personal way that gives death a nightmare terror.  And as for the fading of the artistic impulse, they’ve left not a trace of the paintings and drawings and scratchings of the Old Stone people who came before them.”

“Adults with the minds of thirteen-year-old children.  Thirteen-year-old children with the strength of adults—­and no one to slap them or tell them not to....  After all, they probably only thought of death now and then.  And they never thought of fuel.  They supposed there was no end to that.  So they used up their woods and kept goats to nibble and kill the new undergrowth.  Did these people have goats?”

“I don’t know,” said the doctor.  “So little is known.”

“Very like children they must have been.  The same unending days.  They must have thought that the world went on for ever-just as they knew it—­like my damned Committee does....  With their fuel wasting away and the climate changing imperceptibly, century by century....  Kings and important men followed one another here for centuries and centuries....  They had lost their past and had no idea of any future.. ..  They had forgotten how they came into the land...  When I was a child I believed that my father’s garden had been there for ever....