p. 140 Canon XX.
It is not right for a deacon to sit in the presence of a presbyter, unless he be bidden by the presbyter to sit down. Likewise the deacons shall have worship of the subdeacons and all the [inferior] clergy.
Ancient Epitome of Canon XX.
A deacon shall not sit down unless bidden.
This is another canon to curb the ambition of Levites who wish to take upon themselves the honours of the priesthood also. Spiritual Cores seem to have been common in early times among the deacons and this is but one of many canons on the subject. Compare Canon XVIII of the Council of Nice. Van Espen points out that in the Apostolic Constitutions (Lib. II., cap. lvij), occurs the following passage, “Let the seat for the bishop be set in the midst, and on each side of him let the presbyters sit, and let the deacons stand, having their loins girded.”
Here it should be noted, by the way, that in this canon there is presented a hierarchy consisting of bishops, presbyters, and deacons and other inferior ministers, each with their mutual subordination one to the other.
This canon is found in the Corpus Juris Canonici, Gratians Decretum, Pars I., Dist. xciii., c. xv., in Dionysiuss version.