01Constructing the head

Before you can draw a head truthfully you have to understand it as a three-dimensional object. The classical method doesn't treat the head as a flat oval to be coloured in. It treats it as a sphere with flat planes carved into it — the planes of the forehead, the eye sockets, the cheeks, the planes of the nose, the jaw.

John Henry Vanderpoel's The Human Figure (1907) and Andrew Loomis's Drawing the Head and Hands (1956) are the two most useful guides in English.

The Reilly rhythms

Frank Reilly, who taught at the Art Students League, codified a method of constructing a head from a series of curving rhythms — the forehead and cheek of the shadow side, the brow ridge of the light side, the jaw line. Each is a definite curve, and you check your observation against the underlying construction. Learn to see Reilly's rhythms in every head and you'll rarely produce a portrait that's unrecognisable.

Sargent · Madame X · 1884 · the head turned three-quarters

02Proportions to know by heart

The classical canon, derived from antique sculpture and refined by the academies, gives proportions you should know by heart — not to apply as a formula, but to compare your observations against.

03The features, one at a time

Rembrandt

Self-Portrait

c. 1659 · sixty years of looking at one face

Velázquez

Pope Innocent X

1650 · the most penetrating portrait ever painted

The eye

The eye is not an almond pasted on a flat face. It's a sphere that sits in a socket, mostly hidden by the lids. The upper lid is thicker than the lower and casts a shadow on the white of the eye beneath; the lower lid catches a touch of reflected light. The white of the eye is rarely white — it's a warm grey in shadow, a cool grey in light, sometimes pink at the inner corner. The pupil and iris are circles, foreshortened into ellipses by the angle of view. The highlight on the iris is a tiny, sharp accent placed last.

The nose

Four planes: front, two sides, and bottom. Find the planes and the nose appears; smudge them together and the face goes flat. The bridge, where the side plane meets the front, is the sharpest line in the head. The wings of the nose, where the cartilage meets the cheek, are the softest. Vary the edge.

The mouth

The most expressive feature, and the most frequently bungled. The upper lip is darker than the lower because it's angled inward to the light; the lower catches light directly. The corners go back into the head as much as they go down or up — this is what makes a smile read as a smile. The line between the lips is never a hard contour: it's a series of soft and sharp passages, sharper at the centre, softer at the corners.

The ear

A sculpted form of remarkable complexity, easy to ignore and hard to render. Drawing one from cast once a month for a year will repay you many times over.

04The sitting

A portrait from life is painted in a series of sittings, each two to three hours, with breaks every twenty minutes for the sitter's comfort. Between sittings the painting dries; you can work on it alone, but the principal observation must be made from life, with the sitter in front of you.

The pose

Choose carefully — the sitter will hold it for many hours over many weeks. The head turned slightly off the body, the gaze meeting yours or fixed in middle distance — both work. Avoid extreme expressions; they can't be held. Aim for the natural, settled face the sitter wears at rest.

The light

A high north window, falling on the sitter from the front and slightly above, is the classical portrait light. It models the head clearly without throwing harsh shadows under the brows. Sargent worked this way; so did most of the academic portraitists. A spotlight at forty-five degrees with a fill bounce on the shadow side simulates it when the studio can't offer it.

Vermeer · The Milkmaid · c. 1657 · classical north-window light

05The figure

The full nude figure is the highest exercise in the academic curriculum and the test of every faculty you've trained. The drawing must be sound — the figure must stand or sit or recline on the ground convincingly. The anatomy must be felt — you know where the bones lie beneath the skin, and where the muscles attach. The light must be honest — the figure is a complex form, and the play of light over it obeys the rules of the sphere and the cylinder.

The classical nude is painted from life in a long pose — three weeks of three-hour sittings is a reasonable minimum. Same sequence as any other subject: imprimatura, drawing in paint, dead colour, working layer, glazing, accents.

William-Adolphe Bouguereau

Nymphs and Satyr

1873 · Clark Art Institute, Williamstown · the academic figure at its most polished

Jean-Auguste-Dominique Ingres

La Grande Odalisque

1814 · Louvre, Paris · drawing as the foundation of everything

06Anatomy for painters

You don't need a surgeon's knowledge of anatomy. You need to know:

• The skeleton, in outline, and where each bone surfaces beneath the skin: the clavicles, the shoulder blade, the elbow, the wrist, the iliac crest, the patella, the malleoli.
• The major muscle groups and what they do: the pectorals, the deltoids, the biceps and triceps, the latissimus, the abdominals, the gluteals, the quadriceps, the hamstrings, the gastrocnemius.
• The classical proportions of the figure: roughly seven and a half heads tall, though the heroic proportions of antique sculpture run to eight or even nine.
• The line of action through the body, and the contrapposto — the alternation of weighted and free limbs that gives a standing figure its life.

Two books will give you everything you need: Stephen Rogers Peck's Atlas of Human Anatomy for the Artist (1951) and Gottfried Bammes's Die Gestalt des Menschen. Read them, draw from them, then forget them at the easel.

Know everything; forget everything; paint. Léon Bonnat, to John Singer Sargent