Freemasonry has adopted as Patrons of our Order the Holy Saints John: Saint John the Baptist and Saint John the Evangelist.

There is no suggestion that either of these Biblical characters was indeed a member of the Craft, but rather that the Principles of Freemasonry were embodied by these individuals.

Of these two, it is generally accepted that St John the Baptist is the original patron, and that the patronage of St John the Evangelist does not pre-date the sixteenth century.

Many ancient lodges adopted one or other as their Patron Saint and held their Installation on the respective feast day: 24th June for Saint John the Baptist and 27th December for St John the Evangelist. While many lodges continue to celebrate the 'Festival of St John' after their Installation, most now hold the event on a date to suit the vagaries of personal choice, rather than adhere to the strict liturgical calendar.
Even so, there are those lodges who continue to observe the historical traditions: the Lodge of Edinburgh (Mary's Chapel) No. 1 (S.C.) hold their Installation on 27 December and Cannongate Kilwinning No. 2 (S.C.) hold theirs on 24 June.
While tradition might expect that each lodge hold their Installation on the feast day of their patron saint, given the current proliferation of Lodges, attendances might be severely limited if a strict interpretation were observed.

As the Holy Saints John are the pre-eminent lights in the firmament of Freemasonry, it is appropriate that their feast days should fall close to the summer and winter solstices (21 June and 21 December respectively): on these dates the Sun reaches its greatest southern and northern declination.
As is so often the case, Christian festivals borrow their timings from the more ancient pagan rituals.

Druids would celebrate the winter solstice with great fires lighted on the summits of hills. With the ceremony, the god is feigned to be born and his birth celebrated.

In similar style the lodge, at its installation, lights anew the fire of knowledge and the Master attains the apogee of his career, being invested with his jewel of office, which under the Scottish Constitution includes the Sun in all his glory.