The Talmud says that Moses, before his death, wrote 13 Torah scrolls - one was kept in the Holy Ark, and the remainder was distributed one to each of the 12 tribes. This was an ingenious way to safeguard the integrity of the Torah text, so that all future copies could be checked against the original scrolls written by Moses.
It's interesting that this parsha lists the final of the 613 mitzvot - that everyone is obligated to write their own copy of the Torah. Even if someone inherited a scroll, he must still write his own.
The commentators explain that, today, we fulfill this mitzvah by amassing a library of Torah books - to create an environment with the resources conducive to Torah study.
Yet there's a deeper idea here. The mitzvah to write your own Torah scroll means that we have to internalize the Torah. To get an emotional relationship with Torah, so that our thoughts and actions are always filtered through the prism of Torah. The Torah has always provided Jews with an approach, an outlook, on everything from business to marriage, from tragedy to celebration.
As Rabbi Emanuel Feldman writes:
"Beyond all the good, rational reasons, Torah is the mysterious bridge which connects the Jew and God, across which they interact and communicate, and by means of which God fulfills His covenant with His people to sustain them and protect them.
"When we study Torah, we are not studying an abstract and arcane text of the ancient world. We are studying the way in which God wants us to live on this earth... (We) are in fact engaged in discovering the essence of Judaism, which is to say, the essence of ourselves..."