Vibratiuncula

1750: Elizabeth Carter, [letter from] Mrs. Carter to Miss Talbot (Deal, Dec. 1, 1750); printed in:

Source: wiktionary

[…] I have upon the strength of your recommendation ventured again to look into Dr. Hartley; I was at first sufficiently puzzled with vibrations, but vibratiunculas are beyond all mortal sufferance, and for any thing I am likely to learn by this part of the book, it would be as much to my profit to read the history of Parismus and Parismenus. After all In vain we search the wondrous cause to find How mind on body, body acts on mind. (with many more quotations and quotatiunculas which might be alleged to the same purpose) and all hypotheses about it seem equally perplexed and ineffectual. But however unsatisfactory these kind of systems may be, they are by no means to be treated with contempt. They are the result of great powers of understanding and strong habits of thinking; and an ingenious author who means well, is to be indulged in some few harmless whims, as it often happens (in a way which perhaps it may be impossible for all vibrations and vibratiunculas in the world to account for) that obscure, and even in themselves useless speculations, lead to the discovery of evident and important truths.

Source: wiktionary

There is another illustration, which at least confers more dignity on the subject, than any tale of vibrations and vibratiunculæ can do.

Source: wiktionary

Nothing therefore is more unwarrantable, or more plainly shews the precipitant presumption of modern sciolists, than the familiar use of the general theory of aerial undulations in their attempts to explain the abstruse phenomena of nature (such as the communication of sensation from the organ to the sensorium by the vibrations of a nervous fluid, the reciprocal communication of the volitions from the sensorium to the muscle, nay, the whole phenomena of mind), by vibrations and vibratiunculæ.

Source: wiktionary