In 1504-5 Fra Bartolommeo called upon him for a deed of friendship, which proves that, whatever biographers (building up theories on a word or two in Vasari) may say of his want of steadiness, the friend who knew him best had supreme trust in him. Santi Pagnini, having been removed to Siena as prior, Fra Bartolommeo made Mariotto guardian and instructor of his young brother Piero, signing a contract that Mariotto was to have the use and management of all estates and possessions of Piero, which included several _poderi_ in the country, as well as the house at the Porta Romana (S. Pier Gattolini). In return Albertinelli was to keep Piero in his house, teach, clothe, and provide for him, not, however, being obliged to give him more than "sette (seven) soldi" a month. Albertinelli was also to have a mass said yearly in the Church of S. Pier Gattolini for the soul of Paolo the muleteer, and to use two pounds of wax candles thereat. [Footnote: Padre Marchese, _Memorie_, vol. ii. pp. 36, 37.] The contract was signed from 1st January, 1505, and was to last till 1st January, 1511. It appears that this brother Piero was a great trouble to the Frate, being of a bizarre disposition, and addicted to squandering money; he sold some possessions for much less than their worth, [Footnote: Private communication from Sig. G. Milanesi.] which probably accounts for the singular contract of guardianship. He did not show enough talent to become a painter, and took priests' orders later. About this time Fra Bartolommeo recommenced work, and while he was painting the triptych for Donatello's _Madonna_ (the miniature _Nativity_ and _Circumcision_ in the Uffizi), Albertinelli was at work in the convent of the Certosa, at a _Crucifixion_ in fresco. The painting is extant in the chapterhouse, and is a very fair and unrestored specimen of his best style. The Virgin and Magdalen are very purely conceived figures; the idea of the angels gathering the blood falling from the wounded hands of the crucified Saviour is very tender; there is a great brightness of colouring, and a greenish landscape almost Peruginesque in feeling. Some of his pupils worked with him at the Certosa, and nearly brought their master into trouble. They were not more content with convent fare than was Davide Ghirlandajo, when the only delicacy supplied him at Vallombrosa was cheese; and to revenge themselves, they stole round the cloister after the circular sliding panels by which the rations were sent into the monks' cells were filled, and feasted on the meals made ready for the good brothers. Great confusion ensued in the convent, the monks accusing each other of the theft; but when they found out the real culprits, they made a compromise, promising double rations if the artists would hasten their work and leave them their daily dole in peace.