Anyone who has ever taught adults to paint will tell you that quite often the finished product of the student is virtually indistinguishable from the work of the teacher - at least to the untrained eye. Although it's been almost ten years since I've taught adult students, I witnessed this phenomenon innumerable times, and not always with regard to the work of long-time students. A particularly receptive, particularly adept student, one who took instruction well, often turned out work of professional quality after only two or three paintings - to the surprise and delight of everyone concerned, including themselves. It other cases it took longer, but it very often happened.
I once had an adult student do a landscape (from a photo I'd loaned him) that was virtually identical to the one I'd done and sold just a year or so before. And, to add insult to injury, he sold it for more than I'd got. I was a little surprised and dismayed, but decided to take it as much a reflection upon my earlier instructional efforts as his talent as a painter. The point to this little story is this. Perhaps the greatest difference between the work of a professional and that of an amateur (or student) is not the quality of the work but one of time. The painting I did took perhaps three or four hours. The work of my adult student took something like twenty hours under regular supervision. I don't buy it, but it could be argued that I really painted the landscape twice, the second time through a surrogate. In this case, the man, an elderly, retired gentleman who had taken up painting late in life, I'm sure could have done as well on this particular work without me, it would just have taken longer yet.
It's been said that the hallmark of a professional artist is that he or she makes the difficult look easy. That may be true but we should add that they also do so quickly. The Los Angeles County Museum of Art (LACMA) recently displayed the work of Luca Giordano, the Italian Baroque master painter of the seventeenth century who probably came as close as possible in that age to being an artist of international fame. His nickname translates to "Luca work quickly." His surviving works number in the thousands. The LACMA show alone had nearly 100. In the modern era, it's not too unusual for a particularly prolific artist to have painted several thousands of works over a lifetime, but keep in mind, this was the 1600s, and these were not couch paintings of pastoral landscapes or expressionist renderings of wet city streets dashed off in a few hours for the wholesale "starving artist" market. These were major religious and mythological works each involving numerous figures and complex, often strongly diagonal compositions, their dimensions best measured in feet not inches.
Luca Giordano was born in 1634 in Naples; and it was there he studied under the Spanish painter Jusepe de Ribera. Later he picked up influences as diverse as Veronese, Rubens, Pietro da Cortona and Velázquez. His style was universal and his practice international. He worked all over Italy, in Naples, Florence, Rome, and Venice, as well as in Spain and France. And because he worked quickly, he was also quite wealthy for an artist. The LACMA displayed one of his smaller, better known pieces, St. John the Baptist Preaching, from around 1685, in which he depicts the hermit firebrand as a muscular prophet, glowing with divinity, exhorting his multitudes in the desert. Painted during his Spanish period, works such as this were later a strong influence upon Goya. In fact, unlike so many Post-Renaissance painters, Giordano's work remained popular long after his death in 1705. It continued to influence artists throughout the eighteenth and nineteenth centuries. And, though his paintings were widely collected in the US, he was largely forgotten by the art world during the Modern era. However, if the LACMA show was any indication, the twenty-first century may well see a revival of his popularity.