"Such sins, even if they do not kill all grace in us, do harm, nevertheless; and though they are only venial in themselves, they make us apt, ready, and inclined to lose grace and to fall into mortal sin"

Johannes Tauler, a noted German mystic and theologian of the 14th century, provides an extensive reflection on the nature of sin in this quote. Tauler compares 2 kinds of sin: venial and mortal. In Catholic faith, venial sins are considered less serious breaches of God's law that do not sever the individual's relationship with God, while deadly sins are serious transgressions that can result in the loss of grace if not repented.

Tauler starts by acknowledging that while venial sins do not entirely snuff out grace within the soul, they are not without effect. They "do harm, however", recommending that even these lower sins carry a destructive impact. The damage might not be right away evident, as grace-- comprehended as God's unearned favor and existence-- is not entirely eliminated. Nevertheless, the damage occurs at a subtler, spiritual level.

The phrase "they make us apt, all set, and inclined to lose grace" is especially telling. Tauler is showing a development from venial sins to something more risky. By habitually devoting venial sins, people predispose themselves towards a spiritual desensitization. This habituation can dull one's ethical and spiritual senses, slowly wearing down the ability to discern right from incorrect. Eventually, this state of being "apt, all set, and likely" can pave the way for mortal sin, as the soul ends up being more prone to dismissing God's grace and embracing more severe transgressions.

This development elucidates a key element of Tauler's mystic faith: the interconnectedness of human actions and spiritual wellness. He alerts that the relatively little, daily moral failings can collectively cause significant spiritual destruction. The journey from venial sin to deadly sin is not abrupt; it is a progressive slide facilitated by the weakening of one's spiritual defenses through repeated venial transgressions.

In contemporary application, Tauler's insight acts as a reminder of the value of watchfulness in one's spiritual life. It underscores the requirement for regular self-examination and a conscious effort to cultivate virtues to prevent even the mildest failings from settling and flourishing into more severe offenses. Therefore, it is a call to mindfulness and spiritual stability, motivating individuals to remain unfaltering in their pursuit of grace and ethical rectitude.