Why (not), Mary?

[Donna McCreary]

My thought is that Mary believed Lincoln would have been killed that night no matter where he had been. By the time she wrote this letter to Francis Carpenter, it was well known there had been a conspiracy against the government. If Seward could be attacked in his own bed with a house full of family members, Lincoln could have been attacked in any location.

Whether or not it was Mary's idea to attend the theatre will always be debated. According to the rest of the letter to Carpenter, it was Lincoln whose mind was fixed on the idea of attending the entertainment.