This appears to be Alexius' journal. This is the final entry:
Nothing works. I have tried countless times to go back before the Conclave explosion, before Felix's caravan was attacked by darkspawn, before the Venatori first arrived in Minrathous - without success. The Breach is the wellspring that makes this magic possible, and travel outside of its timeline is impossible. The Elder One's demand that I change the events of the Conclave can never be fulfilled. He may kill me for failing him, but I must protect Felix from his wrath.