“I think,” David Hume’s reedy voice cut through the cramped salon, “that either an idea must be derived from actual experience or there must be no truth to it. Id est, you cannot infer the existence of God from a rose.” They were discussing Tertullian in their tutor’s rundown Grassmarket flat.
“All right,” said Peter, the boy Hume had just interrupted, “forget God, then. Take a unicorn, for example….”
Hume abruptly flushed as if he, rather than their tutor, had just drained the decanter of claret. The other students sat forward in their rickety chairs. “I mean,” Peter pressed, “no one has ever actually seen a unicorn, right? Yet they’re all over medieval rugs and such.”
All eyes were on Hume, but he made no reply, just sat gripping his thin knees with his giant hands. After a moment, the discussion went on awkwardly without him.
That evening after tutorial, Hume flagged a coach and drove down to Ninewells, went straight to the barn without kissing his mother first. They had long since sold the horses to meet expenses, so the stalls were empty and webby, all but the last. Hume slung his arms over the low door and whistled out into the paddock. Out of the gloom clotted at the wood’s edge, white as a lightning bolt, trotted a little unicorn. Nickering happily, it nuzzled Hume with its silky nose, but he just frowned at it.
They had found each other very young in the Ninewells woods on a misty April morning. Little Hume had just escaped his father’s wake. When he saw the unicorn standing shining and forlorn in the dripping clearing, he slung his arm around its slender neck, and it came home with him.
It never left, and it proved a considerable comfort through the lean years following his father’s death. Old Andy, the groundskeeper tasked with feeding it while Hume was away at university in Edinburgh, called it “the wee white pony.” Hume had chalked that euphemism up to the old man’s poor eyesight. But now as he stood and watched the unicorn root around in its trough, Hume became stricken with the fear that only he could see it. Perhaps Old Andy was just humoring the Lord’s poor daffy son by slinging oats into an empty stall.
The thought made Hume shiver. He put out a finger and pressed it against the tip of the unicorn’s horn, blinking first at the pain and then at the pink well left in the ridged skin of his fingertip.
“It is possible,” Hume began shakily at his next tutorial, “for an idea to come upon us with such force and vividity that it is mistaken for an impression of experience. Such, I think, are hallucinations.”
His classmates just watched him warily. He clasped his hands to disguise their shaking. He was dizzy with reading and lack of sleep and food, obsessed by the proximity of an insight that could finally explain the unicorn.
“True enough,” said Peter, “but everything’s a bit that way. Take that chair you’re sitting on. It’s real as can be, but shut it up in the bedroom there, and you can’t for all you’re worth prove it exists. That’s ironic, isn’t it?”
Hume started as if Peter had thrown a book at him. “Yes,” he murmured, “it is.”
After that Hume started eating and sleeping again. He would not, however, see the unicorn, or speak of it. He traveled so often he ran through his allowance, so he secured a post as tutor to the notorious young Marquess of Annandale, George Johnstone, who refused to read anything but bestiaries, myths, and the dubious histories of Marco Polo. Hume made the mistake of mentioning that his father had collected the first English edition of Polo’s travels, and Johnstone insisted on seeing it. They drove to Ninewells, and Hume left the Marquess in the library while he went to settle accounts with his mother. When he returned, the boy had vanished.
He re-materialized at dinner and declared before even touching his soup: “You have a unicorn.”
Hume spat into his napkin and thanked God his mother had gone up to bed with a headache. “They are still common in China and the Americas,” Johnstown rattled on, “but not here. It’s as though they won’t stay where they’re not believed in. Ten years ago a blessing of them was spotted in Lapland, intermingled with the reindeer migration. But when an expedition from the Royal Society went to credit the account, they found no sign.”
“You shouldn’t isolate her so, “Johnstone insisted, eyes luminous, when he found Hume speechless. “Unicorns are the most sociable of creatures. I’m sailing to Newfoundland in a fortnight on family business. Let me take her with me. There are others of her kind there. I have seen them.”
After Johnstone had left, Hume went down to the paddock and whistled. Nothing broke the darkness wavering beyond the reach of his lantern. He was about to turn away when a glimmer of white suddenly flickered like a thought, and the unicorn galloped up to him. Hume put an arm around her neck and wept.
It was the last he saw of her. And as Johnstone turned against him soon after his trip to Newfoundland, Hume had no word of what befell her there–if she were happy, if she had found her kind. Still she haunted every word he wrote. And his critics seemed to sense it, for like Peter they nearly always chose a unicorn to illustrate what they liked or loathed about Hume’s theories.
On his deathbed, his belly distended with cancer, Hume had Young Andy grind some of the unicorn horn he had saved, and he drank it in his tea—not because he believed it would cure him but as an apology of sorts, a cup raised toward Newfoundland. And because it was a comfort to have her there with him again at the end.
The Rookery 