SuttaCentral
Thinaṃ nāma yā cittassa akallatā akammaniyatā; middhaṃ nāma yaṃ kāyassa līnattaṃ.
SuttaCentral
This yet to be translated (if ever) but it seems to hint at thina being a mental quality and middha being a physical quality.
Dictionary: Vedic mid (?) to be fat = medh, as Dhs-a.378 gives “medhatī ti middham.
It would differentiate the two designations, yet they would be conjoined at the same time!
with metta
Actually it has been translated (by Ñāṇamoli as The Guide) but it’s still under PTS copyright. Your passage reads:
“Oppressed by lethargy and drowsiness’: lethargy is any unhealthiness, unwieldiness, of cognizance; drowsiness is any sloth of the body.”
In the Visuddhimagga Mahāṭīkā the view that thīna refers to mental sluggishness and middha to physical weariness is attributed to the monks of the Abhayagiri Vihāra. But the Mahāvihāra monks insisted that since a hindrance is a defilement, only mental phenomena can count as such, for all rūpadhammas are avyākata. And so for them thīna meant sluggishness of citta and middha sluggishness of the body of mental factors.
Could you give an example?