Majjhima Nikaya 2:22
SUJATOSeyyathāpi, bhikkhave, dakkho bhamakāro vā bhamakārantevāsī vā dīghaṁ vā añchanto ‘dīghaṁ añchāmī’ti pajānāti, rassaṁ vā añchanto ‘rassaṁ añchāmī’ti pajānāti;
It’s like a deft carpenter or carpenter’s apprentice. When making a deep cut they know: ‘I’m making a deep cut,’ and when making a shallow cut they know: ‘I’m making a shallow cut.’