But the true focus of the picture lies elsewhere. The painter's real interest is in the man on the right - St Joseph (a half-lit profile) - who gazes in wonder at his wife and child. The 20-year-old Velzquez may have been commissioned to produce a classic, didactic Madonna and Child, but he has managed to imbue it with something of his growing fascination with the human condition. He brings to this painting, as to all of his religious works, a simple humanity. Similarly, his bodegones - the low- life paintings that made up the other side of his early work - possess a sense of everyday spirituality.
This duality is the secret of the young Velzquez currently examined in a show at the National Gallery of Scotland. Here is a portrait of a young man on the verge of self-discovery, using convention to explore the preoccupations that will, in time, make him one of the greatest artists the world has ever known.
The name "Velzquez" is extraordinarily emotive - guaranteeing that this year's Edinburgh Festival crowds will flock to this much-publicised exhibition. In effect, though, its incorporation into the title of the show seems no more than a clever marketing ploy by the gallery's director, Tim Clifford - by now a consummate master at crowd-pulling. Indeed, even as I toured the four galleries that make up this show, the ubiquitous Mr Clifford (who had only that morning made an appearance on Radio Scotland) was there, surrounded by TV cameras and sound equipment, bringing art into the public eye with a spirited (and, in the event, successful) eleventh- hour appeal to save a Guercino for the nation. This man may be a scholar of Renaissance art - but surely his bedtime reading is Machiavelli.
The British public has enjoyed a 100-year-long love affair with Diego Velzquez - largely inspired by critical interest in him during the 1890s, when R A M (Bob) Stevenson (cousin of Robert Louis) wrote, in an influential monograph, "From the first he shows sensitiveness to form, and the taste for solid and direct painting." The Velzquez we have come to know is the artist of grand court portraits - the painter of Las Meninas and the Rokeby Venus. He is the artist described by Sister Wendy Beckett in her current TV series as "unique, one of the very greatest of painters". But this is far from the Velzquez currently on view in Scotland.
If you're expecting a Velzquez blockbuster along the lines of Cezanne or the Scottish National Gallery of Modern Arts' own current Giacometti show, a mile away, you will be disappointed. For, while Velzquez in Seville contains some 50 works, only 20 are by the hand of the master. There are three works after Velzquez, two studio works and seven pieces by Velzquez's teacher, Francisco Pacheco. The rest of the exhibition is a curious, if scholarly, collection of connections and mood-setters, including a group of interesting polychrome wood sculptures of saints. But to blazon Velzquez's name seems optimistic in the extreme. Rather, this show should be called Religious and Low-Life Paintings and Artefacts in Seville, 1610 to 1623. Fine for a thesis - or a Mastermind specialist subject - but hardly the sort of title guaranteed to send ticket sales into overdrive or to set the cash tills ringing with sales of catalogues, postcards, fridge magnets and all the other gewgaws that now appertain to every major public exhibition.
It is true that, along with the superlative Adoration of the Magi, the exhibition does include several other gems from Velzquez's oeuvre - a series of saints that demonstrate an increasing interest in characterisation; the Waterseller of Seville from the V&A; the National Gallery's Immaculate Conception, and the enigmatic Old Woman Cooking Eggs. This last work has long been one of the National Gallery of Scotland's own most popular exhibits, and it is not hard to imagine the scene, some months ago, when an inspired curator - possibly even Mr Clifford himself - came up with the bright idea of using it as the peg on which to hang this year's festival show.
A few phone calls - to friends at the V&A, the National Gallery, the British Museum, the Museum of Fine Arts, Boston (source of the gallery's recent watercolour exhibition) and, of course, to Seville and Madrid, and you have your show.
That is not to say that this is not a worthwhile venture; experienced as an exercise in our understanding of the development of an artist's technique, it is extremely useful.
But, ultimately, it is as dry as the cracked and wizened face of Mother Jeronima de la Fuente who stares down at us from Velzquez's two versions of her portrait. It is not helped by the hang - in which Mr Clifford, as is his way, has "skied" too many of the pictures; nor by the lighting of two of its four rooms, whose yellow walls do nothing to project the artist's palette, producing instead a jaundiced glow. It is fortunate that the only painting in this show that offers a clue to the artist's subsequent greatness - the small Portrait of a Man with a Ruff - is hung close enough to the entrance to avoid this torpor.
It is this image - the severe stare floating in the darkness, above a ruff painted characteristically "wet-on-wet", with trailing ribbons of heavy white that betray a growing preoccupation with capturing the essence of light - that we must keep in mind if we are to come away from this exhibition with any understanding of what the name Velzquez really can convey.
n 'Velzquez in Seville', National Gallery of Scotland. To 20 Oct