Paul Pierce thanks Boston many, many times on Twitter and Instagram (Video)

When the Boston Celtics agreed to trade Paul Pierce and Kevin Garnett to the Brooklyn Nets on the day of the 2013 NBA Draft, the decision represented not just the start of the franchise's new rebuilding period, but the end of the one of the longest relationships between a team and player in recent memory. Since he was drafted 10th overall in 1998, Pierce has been the face of the Celtics, their leader in virtually every possible way.

The separation, even if mutually agreed upon, has brought up a lot of emotions. On Friday, the Celtics thanked both Pierce and Garnett for their service in a full-page ad in The Boston Globe. On Tuesday, Pierce himself took the opportunity to remember all that occurred during his 15 seasons as a Celtic. In a rush of activity, Pierce posted 44 photos of his most memorable moments with the franchise to his Instagram account with the hashtag "#THANKYOUBOSTON." He also put up a video montage set to the Dropkick Murphys' "I'm Shipping Up to Boston," which you can watch above.

The effect isn't just the memory of all that Pierce accomplished, but that he genuinely grew into adulthood as a member of the team. In June 1998, Pierce was a 20-year-old kid — now he's a 35-year-old man. In leaving the Celtics, he's saying goodbye to much more than his long-term employer. Is it any wonder everyone is so emotional?