The likely mythic origins of the diocese are found in the cathedral's chartulary which identified the early bishops—Bean, Denortius, Cormac and Nectan—with Mortlach, in present-day Moray.

[2][3][4] These charters allowed Hector Boece to construct a history that had successive Mortlach bishops, culminating with its fourth prelate, Nectan, who would then move his see to Aberdeen.

A Papal Bull of 1157 by Pope Adrian IV confirmed the existence of a monasterium at Mortlach along with five attendant churches as part of the diocese of Aberdeen.

[7][8] The bull authorised bishop Edward to establish a chapter in his cathedral, giving him the choice of introducing regular or secular canons as his clergy but nothing immediately came of this.

Some were reduced to ordinary parish churches, such as Mortlach and Cabrach, while others, more rarely, transformed into organisations that more closely resembled their former existence.

At Aberdeen, the annexation process may have begun as early as Bishop Edward's tenure and increased in line with the development of the chapter.

Invariably, the vicars were paid meagre pensions and lacked the security of tenure which resulted in inadequately educated clerics to deliver the cure of souls.

[15] The reconstruction of the cathedral began when Bishop Alexander Kininmund (1355–80), probably nearing the end of his episcopacy, heightened the walls of the west towers and the nave.

Bishop Henry Lichton (1422–40) completed what Kininmund had started and established the north transept but left the construction of the central tower incomplete.

Thomas Spens (1457–80) finely furnished the interior and Bishop William Elphinstone completed the central tower begun by Lichton.

Dunbar was also responsible for the armorial-adorned ceiling in the nave, displaying the coat-of-arms of the pontiff, Scottish prelates, and leading European rulers.

His successor, Bishop Kalder (1207–1228), had many canons acting as members of synodal sittings who confirmed his episcopal edicts with an archdeacon as the senior cleric.

[18] By 1445, the chapter consisted of 29 canons—the dean, presenter, chancellor, and treasurer were the dignitaries, the archdeacon—no longer a dignitary—and 24 simple canonries made up the remainder.

The dean was elected to his position by the chapter after taking the solemn oath of fidelity and to uphold the rights, customs and liberties of the cathedral.

The authoritative leader of the chapter was the dean and held total control over all who resided in the cathedral environs—this extended not only to the canons but also to the lesser ecclesiastics and servants.

His responsibilities were to oversee the provision of the music used in the church services, choose the choirboys, see to their education, and employ a suitable song-school tutor.

The fourth and last dignity was the treasurer (thesaurarius) whose duties included being the overseer of the church's treasury—items such as gold and silver drinking cups and expensive apparel.

[24] The expression parochia changed over time from its original meaning in the 12th century of being the territory over which a bishop had authority [nb 2]to its later definition of being a locality that was subject to the ecclesiastic charge of a baptismal church.

A church built from new had to be made of stone, glazed and erected and funded by the parishioners while the chancel's construction had to be at the rector's expense.

Despite this, it became normal for these vicarage settlements to become formally part of the appropriation process and the cure of souls was then dispensed either by stipendiary pensioner vicars or parochial chaplains.

[127] The benevolent founders of these hospitals imposed specific conditions on their altruism—recipients of care were obligated to offer prayers for the souls of their patron(s) who believed that as a result, they would receive a diminution of their time spent in purgatory.

These hospitals served various purposes, specifically, care of: The Fourth Lateran Council of 1215 prohibited clerics and infirmarers from practising surgery if it included blood-letting but herbal therapies would have likely been available for the use of inmates.

[131] The last hospital to be built in the diocese of Aberdeen was the almshouse dedicated to St Mary, and founded by Bishop Gavin Dunbar in 1532 and had room for only 12 old men.

In the Aberdeen diocese, since the Cistercians, Templars, Hospitallers and all of the Friar orders were exempt, the bishop's visitation would have only applied to the houses at Monymusk and Fyvie.