Why does the Torah come in five books?

ASKING THE IMPORTANT QUESTIONS: Why Is the Torah Divided into Five Books? (Dr. Elaine Goodfriend, TheTorah.com).The division of the Torah into five books is not mentioned anywhere in the Bible, yet this division may be ancient and inherent. Already in Second Temple times, Philo speaks of it, and by the early first millenium C.E., the Torah became known by the Greek name, Pentateuch, literally, “