Digital Companion to C. S. Peirce
Some Wit, Wisdom & Bewilderment
To ask whether a given fact is due to psychical or physical causes is absurd. Every fact has a physical side; perhaps every fact has a psychical side. Its physical aspect - as a mere motion - is due exclusively to physical causes; its psychical aspect - as a deed - is due exclusively to psychical causes. This remains true, though you accept every doctrine of telepathy, table-turning, or what you will.
Minute Logic, 1902