Thanks to AllPosters.com I've just purchased a nice reproduction of Carlo Maratti's The Virgin Mary Appearing to St Philip Neri - ideal for an altarpiece...
(I feel the proprietors won't mind if I post a copy here of the image concerned; I think of it as offering them some free advertising.)
St Philip, vested in red for Mass, signifying his devotion to the Holy Ghost, kneels in ecstasy as he beholds Our Lady and Child - Our Lady, seated as befits the Mother of Our Lord and therefore the Queen of heaven, being handed a triple-flowered lily (signifying her perpetual virginity) by a helpful angel, and bearing on her lap her beloved Son and adorèd God, the Infant Jesus, cynosure of all eyes and Desire of all hearts, Who is being worshipped by twelve putti, the Holy Apostles Peter and Paul (respectively bearing the keys of the kingdom and the sword of the Spirit, which is the word of God) - with whom lowly St Philip is ranked as the third Apostle of Rome - and St Mary Magdalen (marked out by the jar of ointment she bears as once she did en route to the Empty Tomb) on whose eve he was born and whom he regarded as a special patroness; Philip and his server (note the Oratorian collar) join in the adoration of the Divine Lamb.
[But stay! Is not St Philip gesturing with the one hand to the Madonna and Child, and with his other to... we who behold this sacred image? Is he recommending us to one another?]
I conjecture that the moment illustrated is perhaps the genuflexion at the words Et Verbum caro factum est, during the reading of the Last Gospel - note the position of the Missal at the Gospel end of the altar, and moreover straight on, not tilted (recall that the side altar cards were not yet prescribed during his life, I recall); and the snuffer for the altar candles lies in readiness on the side step (alternatively, given St Philip's habit of having the candles snuffed out at the Communion of his private Mass, which he drew out to a great length, perhaps this is meant to represent what then occurred, known only to God - but at that part of the liturgy his server customarily withdrew).
The Madonna indeed appeared to St Philip at least twice: once, in a dream, to warn him that the construction of the Chiesa Nuova faced disaster had she not interposed (when the building site was inspected, a great roof beam was found totally unsupported at one end - a deficiency hurriedly rectified by the amazed and grateful workmen!); and again, toward the end of his life, to cure him of a serious illness (he was raised in ecstasy, appeared to embrace someone unseen while weeping tears of joy, and before he returned to his senses asked if those attending had not seen Our Lady - realizing he'd alone seen the apparition, he was filled with that confusion which is the mark of true humility).
As a true "Child of Mary", good St Philip ever had a most tender and filial devotion to the Mother of God, and used to recommend the short prayer "Virgin Mary, Mother of God, pray to Jesus for me," or even simply "Virgin Mother," for - again, in Newman's words - "he said that in those two words all possible praises of Mary are contained."