Grazia was born in Castelnuovo di Valdelsa - he was the son of Francesco di Cristoforo Spinelli, commonly known as "Checco il mugnaio" (Checco the miller) - he rented a mill at the foot of the castle in the Castelnuovo community, on the left bank of the Elsa in a place called "Camagiore" (presently known as "Il Mulinaccio"). The family was not originally from Castelnuovo. Probably during the early fourteenth century, the father Francesco with the oldest of the Spinello brothers and Simone (the youngest) moved to Castelnuovo from a neighboring zone. They were lured by fiscal incentives of the sort that Florence was notorious for offering in newly conquered territories (like the territory of San Miniato, annexed in 1370) in order to win over the sympathies of newly subjected populations. Tax records from 1414 show that he was a Castelnuovo resident, and that in 1427, as a forty-year old, his family consisted of wife, Iacopa (28 years) and children Bartolomeo (1 year) and Verdiana (3 years), who both died prematurely, and the 11 year old Grazia. In 1436, he declared: "I am in the Castelnuovo mill, grinding and doing the work of five people [sto nel molino di Chastello nuovo a macinare et toccha a mia parte delle cinque staia l’uno]. I have a sickness that comes from the flour that gets in my eyes, and I'm almost blind [Et o’ una infermità per chagione della farina che mi va negli occhi quasi sono per acciecare]." In the mean time, his children included Leone (3 ½ yrs), who also died at a tender age, and Elizabeth (2 ½ yrs), while "His son Grazia doesn’t know heads from tails, at the age of 21 he is in the holy Order at Sancto Romeo in Florence [Gratia suo figluolo non sa a metere per testa ne boca, d’anni 21 et a ordine sacro et sta a Sancto Romeo in Firenze]."

From the limited information recorded in fiscal documents, including estimates of their ages, it is reasonable to presume that Grazia was born in Castelnuovo sometime in 1415-1416, and that he entered the priesthood in the parish of San Romeo in Florence. His spiritual guide was probably Priest Stephen di Michele Calzoni. While he was native to Florence, he belonged to a wealthy family with origins in Castelfiorentino. He headed the rectory of the canon of Saint Mary of Castelnuovo from 1415 to 1428, where he met young Grazia and initiated him in his first ecclesiastical role as "altar boy". In 1428, he was nominated rector of Florence’s San Romeo parish, which he directed until 1449. When the young Grazia decided to enter the priesthood, therefore, it was natural for him to see Florence as the most opportune center for his theological studies, and priest Stephen as his personal point of reference. Despite the fact that most of his spiritual and temporal activity took place in the territory of Castelnuovo, which belonged to the Volterra diocese, his formation in the Florentine environment created a strong tie between his character, attitudes and knowledge and the Florentine Renaissance atmosphere, which he witnessed up close and lived fully during his particularly long life - he was still alive in 1497 at the venerable (especially for that time period) age of 82. He may have died that same year - the records from 1502 confirm that he was dead by that time.

He took his priestly vows, and by 11th June 1437, he was already active as "vice- parish priest" in the Coiano parish. During the years 1437-1451, he was rector of the San Bartolemeo church at Santo Stefano, as well as Santo Croce di Retacchio (in the Coiano parish) and San Prospero di Cambiano (in the Sant’Ippolito di Castelfiorentino parish), in addition to being owner of the chaplaincies of Saint John the Evangelist and Saint Dominic, both located in the canon of Saint Mary of Castelnuovo.

The decisive step took place on 26th February 1451 (common style) when, due to the death of Priest Pietro d’Antonio del Volpe of Castelfiorentino, he was made prior of the church of Saint Mary of Castelnuovo: in reality, he remained the de facto prior of Castelnuovo up until his death, even though in 1487 he "conceded" the honor to Simone, son of his cousin Taviano di Simone, and was earning an annual pension of sixteen gold Chamber ducats as, and not by chance, the bursar of the church.

On 21st January 1458 (common style), the Bishop of Volterra approved and confirmed the chapters and concessions (drafted on 14th October 1456) concerning the reformation of the Saint Lawrence oratory, which was constructed by Franciscan friars from Castelfiorentino in the "piazza all'olmo" (all’olmo square) of Castelnuovo. It was subsequently transformed into a hospital, most likely at the initiative of Grazia himself, who was made Spedalingo along with the layman Biagio di Iacopo di Niccolò from Castelnuovo.

The people made a donation on 17th September 1465, endowing the hospital with landed and property goods, with patrons including the municipality of Castelnuovo, Grazia’s cousin, Taviano di Simone (and his male descendants or, in case of extinction, nephews Tonio, Giovanni and Paolo, sons of Elisabetta and Simone di Paolo di Tedaldo) and Florence’s Santa Maria Nuova hospital. The patron interests became a facile source of disputes, and the Pucci and Salviati families from Florence were especially agile in exploiting this context to bolster their economic power in the region. It was not by chance that Pope Alexander IV decided to concede, in 1496, the administration of the hospital to the Congregation of the Valdelsa priests (dedicated to the Virgin Mary and the Holy Spirit), which Grazia himself had founded with six other priests in the canon of Saint Mary in 1486.

Priest Grazia had an uncontestable personality: his cultural knowledge (fruit of his studies in Florence) combined with his "priestly touch" for asset management could only have emerged from a rural setting like that of Castelnuovo in the second half of the 15th century, with more and more land to be conquered first by the Salviati, then later by the Pucci.

The patronage can be witnessed in how the region’s surviving artworks recall this figure. He is depicted on the altar piece of the hospital of Saints Lawrence and Barbara. His image appears more real and mature in the fresco of the Madonna of the Cough tabernacle, a work entrusted to Benozzo Gozzoli in 1484, "above the road on apple tree way", which shows him followed by two boys, probably relatives, the first of which is believed to be Simone di Taviano, future priest. The person kneeling on the left of the Assumption of Mary could be identified as Giuliano di Francesco Salviati, who had his country home in Meleto and knew Priest Grazia: this would broaden the scenario encompassed by this tabernacle. Finally, Grazia’s commissioning of the tabernacle of Santa Maria della Marca (Saint Mary of the Marca) of Castelfiorentino remains the most enigmatic, even in comparison to the Clarisse monastery. This was when, on 2nd February 1491 (common style), in the presence of "magistrate Benoçço Alesi, painter of Florence," Priest Grazia sold his house in the Borgo Nuovo of Castelfiorentino to Berto da Castelluccio for the price of three guilders, and simultaneously sold a piece of land that had been donated to him by the notary Pietro di Barnaba to Sister Brigida di ser Giuliano di Francesco Bardini of Florence, the monastery’s abbess, for twenty-five guilders with the possibility of alienating it to the monks themselves. These operations surely contributed to financing the tabernacle, and with the death of Priest Grazia these goods soon became grounds for contention between the monks and the Pucci family.