Where does the enormous potency of teshuvah come from? How can it erase the past, change the present, mold the future - recreate, as it were?

The power of teshuvah derives from its transcendent nature.

Like Torah, teshuvah preceded the Creation. It is not part of the world, of Creation, of a creative process. It is beyond time, beyond space, rooted in infinity. In the sphere of infinity, past and present fade into oblivion.

Teshuvah is in the heart, in the mind. One thought of teshuvah is enough. For thought, the mind, is not restricted by the limitations of the body.

The mind can traverse the universe in seconds. And the mind - machshavah, thought - is man, the essence of man. Man is where his thoughts are.

Fasting, self-mortification, may be means through which man expresses remorse. They may be acts of purification, of self-cleansing. But they do not constitute teshuvah. Teshuvat hamishkal, penance commensurate to the sin, "to balance the scales," is important. So is teshuvat hageder, the voluntary erection of protective "fences" to avoid trespassing.

Empirical reality may dictate such modes of behavior corresponding to certain forms of weakness. However, these deal with symptoms only.

They relate to specific acts that constitute the external manifestation of sin. They do not touch sin itself. They do not tackle the root and source from which sin grows. That root and source is in the mind, in the heart: ignorance, carelessness, neglect, wrong attitudes, egocentricity, self-justification.

Just as sin is rooted in man's will and mind, so must teshuvah be rooted in man's will and mind.

"He who sets his heart on becoming purified (from ritual defilement) becomes pure as soon as he has immersed himself (in the waters of a mikveh), though nothing new has befallen his body. So, too, it is with one who sets his heart on cleansing himself from the impurities that beset man's soul - namely, wrongful thoughts and false convictions: as soon as he consents in his heart to withdraw from those counsels and brings his soul into the waters of reason, he is pure."

(Note the analogy between teshuvah and the purifying waters of a mikveh.

The Midrash goes a step further: teshuvah is more than a mikveh; it is like the sea, immersion in which also effects purification. A mikveh is subject to limitations of time and space. It is limited to a distinct location (a building), and is not always accessible or available. The sea, however, transcends these limitations: it is always accessible and available, if not in one particular spot then in another.

"Teshuvah is like the sea which is never barred, so that whoever desires to bathe in it can do so whenever he desires." Midrash Tehilim 65:4.)

The tragedy of sin is not so much the transgression itself, to succumb to temptation, for "there is no man on earth..... that he never sins."

The real tragedy, the ultimate sin, is the failure to judge oneself, the failure to do teshuvah, "he has left off to contemplate to do good....does not abhor evil."

Better one self-reproach in the heart of man than numerous lashings.

As the bacteria, poisonous and infectious, are eliminated, their symptoms and outgrowths will disappear as well. And as sins cease, sinners will be no more. Thus teshuvah, the teshuvah that deals with the essence of sin, brings healing into the world.

This is not to understate the external symptoms of sin. For with every transgression "man acquires a kateigar, a prosecutor, against himself." The act of sin assumes reality. It clings to man, it attaches itself to him - leading him further astray in this world only to accuse him later in the hereafter.

On the other hand, everything in Creation is categorized in terms of matter and form (body and soul). The act of sin, its external manifestation, is the matter (the body) of sin, which creates the kateigar. The underlying thought, the intent, the will or passion that generated the transgression, is the form (the soul) that animates and sustains that body.

Self-mortification attacks that body and may destroy that matter. But only a change of heart, conscious remorse, is able to confront its form, its soul.

Only the elimination of the thought, intent and desire that caused the sin, will eliminate the soul of the kateigar. And when deprived of its soul, the kateigar ceases to exist.

Thus "rend your heart and not your garments, and return unto G‑d, your G‑d, for He is gracious and compassionate, long-suffering and abounding in kindness....." When rending the heart in teshuvah there is no need to rend one's garments.