Our ability to decrease suffering and increase happiness in our lives is directly proportional to, among other things, our sharpness of discernment.
Our sharpness of discernment is proportional to, among other things, the degree to which we speak truth.
When we ignorantly speak untruth, in our deepest conscience know we are doing wrong. Knowing we are doing wrong, the mind is agitated and angst-ridden.
The mind being agitated and angst-ridden, one is unable to discern clearly. Poor decisions seem like good decisions, good decisions seem like poor decisions. Non-benefit appears beneficial, benefit appears non-beneficial.
One who ignorantly speaks untruth as a chronic habit: such a mind, being wracked with guilt and confusion, seeks out self-medication through the various means. Being steeped in a habit of self-medication, the mind is further dulled, further unable to discern clearly. Suffering multiplies, yet the one who suffers is unable to see the source of that suffering.
When we non-ignorantly do not speak untruth, in our deepest conscience we know we are not doing wrong. Knowing we are not doing wrong, the mind is neither agitated nor angst-ridden.
The mind being neither agitated nor angst-ridden, one is able to discern clearly. Good decisions are seen as good decisions, poor decisions are seen as poor decisions. Benefit appears beneficial, non-beneficial appears non-beneficial.
One who non-ignorantly does not speak untruth as a chronic habit: such a mind, being not wracked with guilt nor confusion, does not seek out self-medication through the various means. Not being steeped in a habit of self-medication, the mind is not further fulled, not further unable to discern clearly. Suffering does not multiply, and the one who suffers not is indeed able to see the sources of suffering.
Thus, to increase happiness and decrease suffering in our lives–and thus contributing to the increase of happiness and the decrease of suffering in the lives of those around us–let us practice skillfulness in speaking truth and in discerning clearly, let us not practice unskillfulness in speaking untruth and in not discerning clearly.
satya pratisthayam kriya phala ashrayatvam
To one established in truthfulness, his very word becomes binding on objective reality.
Yoga Sutras 2.36, translated by Swami Kriyananda