Consistency is the quality of always being the same and is an important principle in both Buddhist philosophy and ethics. To be genuine, a truth must be consistent in that it is not contradicted by reality. For example, the Buddha's statement `All conditioned things are suffering' (Dhp.278) is rightly called a noble truth because it is impossible to find a conditioned thing that offers total and lasting satisfaction. Also, two contradictory concepts, statements or beliefs cannot both be true, although they may well both be false. This is what the Buddha meant when he said: `Truth is one' (Ekaü hi saccaü, Sn.884).
Ethical truths must also be consistent. Certain behaviour cannot be wrong in one situation and right in another. Thus it is wrong to kill, no matter what the circumstances. However, the Buddha recognizes that there is a difference between killing out of rage or jealousy and killing in self-defence. The first is completely wrong while the second can be what he called `mixed' (vãtimissa), i.e. a mixture of different degrees of wrong and right (M.I,318).
Consistency is also important in many areas of the spiritual life. The Buddha said that the sign of a worthwhile teacher is that there is consistency between how he or she acts in public and in private and that their good qualities endure through changing circumstances (M.I,318). He also said that a characteristic of the enlightened person is a harmony between their understanding and their actions (vijjàcaraõasampanno). For example, they truly understand that forgiveness is the highest form of letting go and, therefore, they are able to forgive anyone, even those who have been very cruel to them. The Buddha said that he `preaches what he practises and he practises what he preaches' (It.122). This was because he had understood the truth at the deepest level so that it was completely integrated into every aspect of his being. For him, consistency was effortless and natural.