Besides the Confraternity of Saint Catherine of the Night, the other important lay Company with headquarters in the underground rooms of the Hospital was that of the Disciplinati (Flagellants). This Company was founded, in all probability, during the thirteenth century, the period in which its first statutes were issued, but its legendary origins went back to the early Middle Ages, if not even to the time of Saint Ansanus, the baptizer and Patron Saint of Siena, who died a martyr, according to the tradition, in the nearby street of the 'Fosso' (ditch) which now bears his name. The bylaws dictating the requisites for admission and belonging to the Company demanded a rigorous selection of the persons aspiring to membership, chosen from among the most authoritative figures in the ruling class of Siena, who were required by the strict, highly detailed rules to follow an austere way of life, but they also enjoyed great prestige as political counselors and administrators of public charity. Furthermore, the adoption of an insignia with the cross and two ‘disciplines’ (whips) hanging from it symbolized the full adherence of the brothers to the sacrifice of Christ and the penitence of flagellants.
Between the thirteenth and fourteenth centuries the Company counted among its members some outstanding personalities in Sienese mysticism, such as Saint Bernardo Tolomei and the Blesseds Andrea Gallerani, Pietro Petroni, and Giovanni Colombini, as well as a group of disciples of Caterina Benincasa, including Gabriello di Davino Piccolomini, Sano di Maco Ianaiolo, and Stefano di Corrado Maconi. In 1379, after the outbreak of the Western Schism, Saint Catherine wrote to the prior and the brothers of the Company, exhorting them to support the cause of Pope Urban VI against the antipope Clement VII not only 'spiritually' with their prayers, but also 'temporally' by using all their influence to persuade the Sienese government to support the 'true vicar of Christ'. At the beginning of the fifteenth century, before entering the Franciscan Order, the young Bernardino degli Albizzeschi (Saint Bernardine) belonged to the confraternity, and his vocation matured in his assistance to the plague victims in the hospital upstairs.
During the age of the Counter-Reformation, the Company was a center of worship, officiated frequently and regularly by five chaplains, the number of altars in the oratory, while the brothers distinguished themselves for their works of charity in favor of indigents, prisoners, and the neediest religious organizations. Its assets grew as a result of numerous donations and legacies made between the sixteenth and eighteenth centuries by various Sienese patricians for the salvation of their souls, so much so that in 1783, when it was decided to levy a special tax to contribute to the reform of the University of Siena, the Company was taxed as the institution that was by far the richest among all the religious organizations of the time. Two years later, however, the suppression of the lay confraternities in Tuscany decreed by the Grand Duke’s government spared the patrimony of the Company, which was changed into a secular institution with the new name of 'Società di Esecutori di Pie Disposizioni' (Society of Executors of Charitable Directives), the association which for more than two centuries, up to the present time, has continued to exercise important social and economic functions in Siena and the territory of the ancient Republic.
The numerous rooms of the Society’s headquarters, located very close to the oratory of the Company of Saint Catherine of the Night, contain a significant collection of art works, which was enriched several years ago by the discovery of an interesting early fourteenth-century fresco cycle illustrating the Thebaid, which came to light along the stairs leading to the Society’s headquarters. Among the other art works, especially noteworthy is the beautiful wooden Crucifix above the left altar of the oratory, which according to tradition led Saint Bernardine to don the habit of the Franciscans.