I have no idea, nor do I care, since the value of having a somber penitential season of fasting and prayer leading up to the commemoration of the passion, death and resurrection of Our Lord seems quite obvious. Pagan things are bad only insofar as they contradict the teachings of the faith, and if they don't, they can be "baptized", like Christmas trees, to serve the inculturation and growth of the Faith. I think Lent is a terrific reminder of our fallenness and need for Christ's redemption. The fasting and somberness appeals and teaches our weak human senses. When I was a Protestant, there was not nearly an emphasis on our sinfulness. The mainstream Protestant churches have pretty much eliminated the concept of individual sin.
I agree with you.
However, I'll add that the author of that work can't know very much about Scripture to say that the practice of Lent is derived from pagan practices.
When 40 days appears in the Bible it is an indicator of a time of waiting, suffering, longing for the appearance of the Lord. It is 40 days of preparation and/or reparation: Noah, the Israelites in the desert, the 40-day encounter of Christ with Satan, the 40 days after the Resurrection to Pentecost. These are just the more signal uses of the term 40 in Scripture to indicate a time of waiting on the word, the voice or the action of God. Ther are more.
Lent is the 40 days of fasting and prayer to honor the 40 days Jesus endured before opening up his public life. For ourselves and for our salvation, He won victory over Satan with prayer and fasting--prayer and fasting is what Jesus Himself commanded us to do in order to win over temptation.
We become doers of His word and life when we enter into this "desert place" to fast and pray.
I never thought of it that way.