'roots', also called hetu (q.v.; s. paccaya, 1), are those conditions which through their presence determine the actual moral quality of a volitional state (cetanā), and the consciousness and mental factors associated therewith, in other words, the quality of karma.
There are 6 such roots, 3 karmically wholesome and 3 unwholesome roots, viz.,: greed, hate, delusion (lobha, dosa, moha), and greedlessness, hatelessness, undeludedness (alobha, adosa, amoha).
In A.III.68 it is said that greed arises through unwise reflection on an attractive object, hate through unwise reflection on a repulsive object. Thus, greed (lobha or rāga) comprises all degrees of 'attractedness' towards an object from the faintest trace of a longing thought up to grossest egoism, whilst hatred (dosa) comprises all degrees of 'repulsion' from the faintest trace of ill-humor up to the highest pitch of hate and wrath.
The 3 wholesome (kusala) roots, greedlessness, etc., though expressed in negative terms, nevertheless possess a distinctly positive character, just as is also often the case with negative terms in other languages, for example, the negative term 'immorality', which has a decidedly positive character.
Thus, greedlessness (alobha) is a name for unselfishness, liberality, etc., hatelessness (adosa) for kindness or goodwill (mettā), undeludedness (amoha) for wisdom (paññā).
"The perception of impurity is to be developed in order to overcome greed (lust); loving-kindness in order to overcome hate; wisdom in order to overcome delusion" (A.VI.107).
"Killing, stealing, unlawful sexual intercourse, lying, tale-bearing, harsh language, frivolous talk, covetousness, ill-will and wrong views (s. kammapatha), these things are due either to greed, or hate, or delusion" (A.X.174).
"Enraptured with lust (greed), enraged with hate, blinded by delusion, overwhelmed, with mind ensnared, man aims at his own ruin, at others' ruin, at the ruin of both, and he experiences mental pain and grief. And he follows evil ways in deeds, words and thought... And he really knows neither his own welfare, nor the welfare of others, nor the welfare of both. These things make him blind and ignorant, hinder his knowledge, are painful, and do not lead him to peace."
The presence or absence of the 3 unwholesome roots forms part of the mind contemplation in the Satipatthāna Sutta (M.10). They are also used for the classification of unwholesome consciousness (s. Tab. I).
See The Roots of Good and Evil, by Nyanaponika Thera (WHEEL 251/253).