Arani Sutta

There are five indriyas: those of ease, discomfort, happiness, unhappiness and indifference. Just as from the rubbing together of two sticks warmth and heat are produced, so, from their separation, warmth and heat, thus born, are quenched; similarly from contact, experienced as agreeable, arises the faculty of ease (sukhindriya), etc. S.v.211-13.

Dictionary of Pali Proper Names, G P Malalasekera (1899-1973), which is available as printed version from