David Boreanaz' father, Dave Roberts, makes a brief appearance as a person using a copier. Dave is a longtime weatherman in the Philadelphia area.
The one hundredth episode.
This 100th episode became, basically, the origin story of Bones & Booth plus how Booth got involved with the Jeffersonian and the people that work for Dr. Brennan.
The title is a subtle rewording of the Synergy Principle, whereby the whole is considered greater than the mere sum of its parts.