Freeeeedom

Freeeeedom

"The future has not yet happened. But it is on that account less necessary than the past, since the past did not become necessary by coming into existence, but on the contrary proved by coming into existence that it was not necessary." (I don't have page numbers)

Can we discuss Kierkegaard's use of the words "Freedom" and "Necessity"? Why would the past's coming into existence prove its non-necessity?