It wasn’t political, it had no cultural agenda, and it never really pushed the boundaries of what was considered permissible on the comics page. So how did Charles Schulz’s “Peanuts” endure for 50 years in countless American papers? Perhaps it was the simplicity of the art and the humor, or the tender way in which Schulz portrayed the most hapless characters, or maybe it was just that Charlie Brown seemed to represent a bygone era of innocence for which many Americans long. This week, the first edition of what will be a complete reprinting of every Peanuts strip ever drawn is being released, authorized by Schulz’s widow against his previously expressed wishes.