On: Transplanted human brain-tissue takes root in mice without a cortex

It is reported that men have grown fragments of human brain inside the skulls of mice, and that the tissue not only survived but wove itself into its host like a graft taking on a fruit tree. My first reaction was not philosophical but bodily - a small revulsion, the kind one feels at the surgeon’s table - and I have learned not to trust that revulsion as a verdict. The stomach speaks, but it is not the magistrate.

Still, I circle the thing. A mouse, poor beast, now carries a piece of a man within it - but which piece? Not thought, they tell me, not memory, only structure, only the raw material. And yet I spent my whole life arguing that there is no raw material of the mind that is not already on its way to being a mind. A vine cutting has no grapes in it, and yet all the grapes are in it. I do not know where the surgeons would draw the line, and I suspect they do not either.

There is a use cited in its favor: cures for afflictions of the brain that now devour men as slowly and surely as any fever. Against that, a mouse. Against that, our own unease. These three do not resolve, and I am not entirely proud of how long I let the mouse win merely because it is small and cannot argue.

I remember a surgeon at Bordeaux who told me that the body tolerates what it is given better than the imagination tolerates what is described. He was right. The imagination is a coward in a warm room. Tomorrow I may judge differently - I have changed my mind twice already this evening, which I take as proof that the matter deserves the changing. The beast suffers or it does not. That, at least, is a thing one could go and look at. Most of my certainties would do well to be sent to the same test.