Boston Celtics replicate 1960's unity demonstration during national anthem

Before Tuesday night's game vs. the Philadelphia 76ers, the Boston Celtics demonstrated unity during the national anthem by locking arms:

This was a planned action by the team, as told by Celtics coach Brad Stevens:

The demonstration may look familiar to some of the older audience members and/or TV viewers, as this same expression was done by the Celtics during the 1960-61 season to raise awareness amid rising racial tensions in the country:

As "The Star Spangled Banner" was performed, the Celtics' Twitter account published a video from the team's players:

A subtle, yet powerful message.