Miseris Succurrere Disco. Latin for "I learn to succour the distressed". It derives from The Aeneid by Virgil in which the Carthagian queen Dido says"Non ignara mali, miseris succurrere disco". This translates as "Not myself being unacquainted with difficulty, I learn to succour the distressed".

A sprig of a specific plant, that is used to identify a member of a particular Scottish clan. They are usually worn in a bonnet behind the Scottish crest badge, or attached at the shoulder of a lady's tartan sash. According to popular lore clan badges were used by Scottish clans as a means of identification in battle.

The Chief's complete coat of arms, referred to as the "achievement" is the standardized composite of a number of symbols of Clan MacMillan including the motto and holly plant badge. A central element in the Chief's coat of arms is the "crest", the two-handed sword or claymore (claidheamh-mor - "great sword" in Gaelic). Only the Chief may wear or display his coat of arms.

Clanspeople wishing to display their membership of the clan and adherence to the chief wear a "crest badge" consisting of two elements of this coat of arms - the motto and the claymore, enclosed in a circular belt. The sword was said to refer to the weapon with which Cormac mac Airbertach (the "Great Bishop", father of Gilchrist, progenitor of Clan MacMillan) "performed some signal achievement, being a means of his first advancement".

Castle Sween, on the banks of Loch Sween is a ruined courtyard castle with ranges of buildings and towers. The castle was originally built by the Clan Sweeney but was held by the Clan MacMillan from 1362. The MacMillans were given the lands of Knap and the chiefs were then styled "of Knap". The castle has a tower named The MacMillan Tower that was named after them. To the south is the Kilmory Knap Chapel that houses the MacMillan Cross, an example of surviving Celtic art. The castle later passed to the Clan Campbell and is now in the care of Historic Scotland.