I waive the quantum o’ the sin,
The hazard of concealing:
But, och! it hardens a’ within,
And petrifies the feeling!

In Scots-inflected diction, the speaker sets aside (“waive”) the exact measure (“quantum”) of wrongdoing and even the practical risk (“hazard”) of keeping it hidden, to stress a deeper moral-psychological cost: concealment corrodes the inner life. The image of the heart “hardening” and feelings “petrif[ying]” suggests that secrecy does not merely avoid consequences; it gradually deadens empathy and moral responsiveness. The stanza frames confession or openness as a safeguard for one’s humanity, implying that the gravest damage of vice may be the way it numbs the capacity to feel—remorse, tenderness, or fellow-feeling—rather than any external punishment.