Simplify the following text for a Grade 7 native English-speaking person.
Original: Sagan was a user and advocate of marijuana . Under the pseudonym `` Mr. X '' , he contributed an essay about smoking cannabis to the 1971 book Marihuana Reconsidered .
Simplified: Under the name `` Mr. X , '' Sagan wrote about pot smoking in the 1971 book Reconsidering Marijuana .