This is the central
panel of the altarpiece.
Bruges, ca. 1490
Oil, oil gilding, and silver on oak panel, 54 1/4 x 59 in. (137.8 x 149.9 cm)
The Cloisters, New York City (accession number 61-199)
In the scene on the upper left Bishop Valerius of Hippo ordains Augustine as a priest. (At the moment shown he is anointing Augustine's hands.) Below left, Augustine preaches in Hippo before his bishop. According to the Golden Legend (html or pdf), Valerius' mother tongue was Greek and he needed Augustine to preach to the people in Latin. The museum's description identifies the woman with the rosary at Valerius' left as St. Monica. This would be anachronistic (because Monica died before Augustine returned to Africa from Milan), but then so is the rosary.
The central scene appears to depict Valerius consecrating Augustine as Bishop of Hippo. The three men in white are minor clergy charged with various sacred items associated with baptism: a tall candle, an aspergillum (used at solemn masses for sprinkling the congregation as a symbol of their baptism), a censer, a box for salt (a symbol of preservation from sin to be placed in the baptized person's mouth), and the two ampullae of chrism or blessed oil. The middle man holds the book from which the celebrant will read parts of the liturgy.
description of the panel on the right says Augustine is
preaching on the Trinity, counting off the number three on
his fingers. The upper right shows the "Parable of the
More of St. Augustine