Lo Lishma

Le'olam Ya'asok Adam BeTorah uVimitvot shelo Lishma sheMitoch sheLolishma Ba Lishma. An interesting explanation based on an interpetation of the first Lubavitcher Rebbe the "Baal Hatanya". The simple and intuitive understanding of that famous ma'amar chazal is that if one learns torah (we will be focusing on the learning torah aspect of that ma'amar rather than the mitzva aspect for this discussion) is that if one studies Torah for a different purpose other than for its sake (many rishonim and acharonim including the famous 4th perek of sefer Nefesh Hachaim deal with the meaning of "Lo Lishma" and "Lishma") although not optimal it is still preferred because by studying Torah for an ulterior motive that person studying will eventually study Torah for the right reason. The Baal Hatanya says (Tanya, Chapter 39) that the Torah studied in a "Shelo Lishma" manner is the lowest form of Torah and doesn't even leave this world however when one does Teshuva then the Torah that he learned even in a "Shelo Lishma" fashion rises to a new level.

I understand this in possibly a different way (maybe this is what he meant). By way of analogy; take two people who are not spiritually connected but both started out in a Torah environment. One, leaves that Torah environment because he feels that learning Torah in an impure manner is a violation to his soul and possibly a chillul hashem. He leaves the world of Torah and continues living his life in any manner that suits him. Another, continues studying Torah although he is not satisfied and knows that his Torah is not what it should be, doesn't fulfill him and for that matter might even be Torah which might be considered "Sam Hamaves". However, both those people later in life discover the truth and feel pulled to the true light of the Torah and begin studying Torah the way it was meant to be studied. Let us examine these two men. The one who had left the act of studying and has no knowledge of Torah is literally starting fresh. How much Torah can that person learn and know in the remaining time he has on this earth? he will remain an Am Ha'aretz because of all those years that he missed out on his studies. On the other hand, the other person, the one who studied his  whole life can turn into an instant Talmid Chacham. Because of the fact that he, by that time, ostensibly has so much Torah ( a whole lifetime of study) within him he is now automatically a great man. A man who knows the truth, strives for the truth and knows how to interpret all his Torah knowledge into action. That second person is the quintessential  "Le'olam Ya'asok Adam BeTorah uVimitvot shelo Lishma sheMitoch sheLolishma Ba Lishma" the Shelo Lishma has now turned into lishma because now he is a man of truth.

When one does Teshuva, everything he is or had become over those years of being a sinner is now transformed into his Ba'al Teshuva being. Everything he acquired over that period is still part of him.