What is the content of the earliest review for the "Stuff You Should Know" podcast?
"Stuff You Should Know" is the title of podcast; earliest refers to Min(created_at)
SELECT T2.content FROM podcasts AS T1 INNER JOIN reviews AS T2 ON T2.podcast_id = T1.podcast_id WHERE T1.title = 'Stuff You Should Know' ORDER BY T2.created_at ASC LIMIT 1