Since the end of the 2nd century, the cult of the virgin Thecla is documented (the liturgical solemnity falls on 24 September), who had not hesitated to shed her blood for Christ the Lord. Many churches were built in her honour: the ancient Cathedral in Milan was dedicated to her.
Bishop Ambrose would repeatedly propose Thecla as a model of faith and constant perseverance in love for the Saviour to consecrated virgins. The name of this Martyr has been inscribed since ancient times in the Eucharist Canon in the Milanese liturgy.
In Duomo, at the beginning of the Capitular Mass, on the Solemnity of the martyr Saint Thecla, Patroness of the Cathedral’s Parish, one of the most suggestive rites of the Ambrosian liturgy takes place: the Rite of the Lighthouse. This custom most certainly derives from an even older tradition, probably dating back to the 7th century and, in the Milanese context, precisely in reference to the Duomo’s liturgy, to at least the 12th century.
The rite characterised some particularly important celebrations. When the entrance procession had reached the altar, the pharus was lit, a type of chandelier made up of a series of lights arranged in a crown, above which was placed a ring of cotton wool. This cotton wool, upon being burnt, would light the individual lamps.
The interpretation that scholars give of this ancient rite fluctuates between the purely functional (rapid lighting of all the lamps at once) to the allegorical (the image of the triumph and glory of the Martyrs, in whose feasts this rite was celebrated), as well as also to that which sees in the lighting of the lighthouse an element that simply serves to make the start of the liturgical celebration particularly solemn on these special days.
Over time, the lighthouse transformed from a crown of lamps to a globe of cotton wool, hung at the entrance to the presbytery, which the celebrant lights themselves with three lighted candles fixed to the top of a pole, at the end of the opening procession and the singing of the traditional Kýrie eléison, before going up to the altar. In this case, the meaning of the rite alludes to the Martyr’s sacrifice of life.