That Was Then, This is Now (idea)

This is a phrase that is generally used in an argument or when making a point. Basically it means that it doesn't matter what happened in the past, because the past is the past. What is important is what happens now.

It is also the title of a novel by S.E. Hinton, who wrote The Outsiders. The book was made into a movie in 1985 that starred Emilio Estevez and Morgan Freeman.