Mūla: 'roots', also called hetu, see: paccaya, are those conditions which through their presence determine the actual moral quality of a intentional state cetanā and the consciousness and mental properties associated therewith, in other words, the quality of kamma. There are 6 such roots, 3 kammically advantageous and 3 disadvantageous roots, viz.,: greed, hate, confusion lobha dosa, moha and greedlessness, hatelessness, unconfusedness 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 advantageous 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, generosity, etc., hatelessness adosa for kindness or goodwill mettā unconfusedness amoha for understanding paññā.
The perception of impurity is to be developed in order to overcome greed lust; loving-kindness in order to overcome hate; understanding in order to overcome confusion; A. VI, 107.
Killing, stealing, unlawful sexual intercourse, lying, tale-bearing, harsh language, frivolous talk, covetousness, ill-will and wrong views see: kamma-patha these things are due either to greed, or hate, or confusion; A. X, 174.
Enraptured with lust greed, enraged with hate, blinded by confusion, 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 disadvantageous roots forms part of the mind contemplation in the Satipatthāna Sutta M. 10. They are also used for the classification of disadvantageous consciousness.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.