Sinning as the act of sinning has its roots in 'original sin'. For John Wesley, sin cannot reign in the regenerated, but does remain, even though past sin is pardoned and the stain of guilt removed. While it is too simplistic to limit his understanding of sin to 'a voluntary transgression of a known law' (which is certainly scriptural, even if not the full biblical understanding of the nature of sin), this definition is vitally important for his teaching on the state of a justified Christian who does not knowingly sin, and those who have gone on to Christian perfection or 'perfect love'. For those who have advanced in the Christian life, the principle of sin has itself been destroyed and the carnal mind remaining in the believer utterly cleansed. But Wesley recognized the continuance of 'ignorance, mistake, temptation, and a thousand infirmities' in those who had experienced a second distinctive work of grace. He often spoke of sin in terms of a disease from which we need to be healed - a therapeutic concept he shared with Eastern Orthodox theologians. (Cf. Charles Wesley's 'The seed of sin's disease / Spirit of health remove' etc.) The line he drew between actual sins and human weaknesses has been considered by critics as dealing too loosely with the reality of inward, unrecognized, involuntary sin.