geometer, n.All

Geometer (n.) is ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠a motor subject: he knows the relations he studies only by describing them, at least potentially, with his body.

A Geometer (n.) is ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠one whose chalk lines on a real blackboard ground nothing: whether he is drawing them or hallucinating them makes no difference to his proof.