Everyone can appreciate how valuable artists' eyes are, but not everyone then goes on to think about the different ways artists use their eyes.

Of course, seeing the canvas, paper, marble or other vehicle for artists' expressions is key. The subject of the art piece, often objects gazed at by the artist, is also looked at by the artist. Yet the different techniques of using one's eyes as an artist dictate many different approaches to art. Plein air art requires careful observation in person, usually of landscapes.

Life drawing too implies careful study of the nude model posing, as do still life studies which are usually based on arrangements made and set up for the artwork. Portraiture gets even more decisive, obviously, because a portrait implies a need to reflect some fidelity to the person being depicted. However, the methods of achieving that portrait are varied; one in particular depends very much on the use of the artist's eyes. I am referring to the use of sight-size, when an artist sets up the easel at such a distance that the subject of the portrait (or life drawing and painting too) is the same size as the image being created. Few artists learn this method today, but artists as diverse as Henry Raeburn, Joshua Reynolds and John Singer Sargent all employed this way to convey a unity of impression in their art, rather than copying all the details. A few ateliers do teach artists how to use and trust their eyes in this fashion - Charles H. Cecil's Studio in Florence, Italy, is one, the Bay Area Classical Art Atelier in California is another, the New York-based Grand Central Academy of Art is yet another.

Working directly from life for drawing and painting is a time-honoured tradition down the centuries for artists - learning to trust one's eyes as you seek to capture the image. Quickly capturing the gesture of a moving person, the characteristic flight of a certain kind of bird, the essence of flowing water, the gait of an animal - all these require careful observation from eyes that become more and more trained as the artist grows more experienced. Practice does indeed make perfect or nearly perfect, as the eyes learn to observe. As an aside, I was fascinated recently to read about a current exhibition, "Michelangelo: Anatomy as Architecture", at the Muscarelle Museum of Art at The College of William and Mary through April 11. Twelve drawings on loan from the Casa Buonarroti in Florence apparently are unusual in that they reveal Michelangelo jotting down visual ideas in a hurry, alongside verses of poetry and various notes. We associate Michelangelo drawings with wonderfully accomplished and often very finished works, but this exhibition includes works that show a much more down-to-earth approach to devising and executing an idea. Apparently it is obvious from some of these drawings that Michelangelo was carefully scrutinising ancient sculptures for his human figures, as well as using his knowledge of direct dissection, after he had peered carefully at muscles and tendons in human bodies - in other words, using his eyes a lot.

There is another aspect to artists' eyes that is vital and fascinating. In the March 2010 edition of Art+Auction, Marisa Bartolucci wrote a long and interesting article on "Zen and the Art of Axel Vervoordt". She recounted that it was apparently the Belgian painter, Jef Verheyen, who taught Vervoordt about the Zero movement and introduced him to a fresh manner of seeing. "The way one looks at things is of the utmost importance. You must feel things with your eyes" (my emphasis). This is a wonderful concept, going to the heart of any art, whether it be the eyes of an artist or those of someone viewing a created artwork. Trained eyes, which imply study, practice and much thought in many cases, allow deepened appreciation and skills. Everyone is enriched by the eyes of artists and art-appreciators.