Complexity of Tara brooch has golden geometric ratio

THE COMPLEXITY of the Tara brooch goes deeper than the creatures that line its metal edges.

THE COMPLEXITY of the Tara brooch goes deeper than the creatures that line its metal edges.

Dr Michael Brennan dissected its symmetry and geometry at the National Museum of Ireland yesterday afternoon as part of Maths Week 2011.

He pointed out that many different types of symmetry, including mirror images and rotation, are used repeatedly throughout differing aspects of the brooch. Some who studied Celtic art, he added, have debated whether the piece fits the famous golden ratio, those geometric proportions claimed since the ancient Greeks to be most pleasing to the human eye.

If all the designs fitted the golden ratio, Dr Brennan said, it would mean more than it “just looks nice”. It would mean the design came from geometry.

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Even if the golden ratio and other mathematics were used to create these intricacies, it did not necessarily mean that the artisans hundreds of years ago realised what they were employing, or even that it was maths.

“Somewhere between artists and mathematicians lie craft workers,” said Dr Brennan, and they use mathematical methods of construction and design without even thinking about them.

He said the artisans who created pieces like the Tara brooch could be considered the mathematicians of their time.