A SHORT HISTORY OF THE BIRETTA
The biretta is thought to have developed from a soft cap worn by clerics to keep their heads warm in the cold, unheated churches of the middle ages. This may have taken the form of a skullcap at first, then grew larger to keep a greater area of the head warm. Its origin is probably the same as the academic cap, which takes the form of a biretta in many continental universities (coloured according to the faculty), and which developed into the mortar-board seen today in English and American universities.
In time the soft cap became square-shaped and developed soft peaks at the corners to enable the clergy to remove it easily. These peaks are the origins of the ‘blades’ on birettas of today.
By the 16th century the biretta as it is known today was universally worn. At first it was a black biretta for higher ranks, but in the 16th century its use was extended to all ranks of the clergy. During the next century, cardboard was introduced to help the cap maintain its square shape and to emphasise the blades on the top. In Spain, however, there were no blades, and the birettas took the form of square caps with round ridges and sharp points on the corners. These birettas are still in use in many parts of Spain.
Pope Leo XIII permitted colour to be introduced, so that bishops could wear a violet biretta. Cardinals already wore a scarlet one.
The tuft, or pompom, on the top of the biretta was a French invention, soon followed almost universally except by the Jesuits in particular and by a number of religious canons (who wore four blades) such as the Premonstratensians.