What is an illustration?

51,200 years ago, on a cave wall.

The oldest picture we know of that shows something happening is on Sulawesi, in Indonesia. Three figures and a wild pig, painted at least 51,200 years ago.

The paint was earth with iron in it, ground to a powder and mixed with water. Red ochre gave red, and charcoal or manganese gave black. People put it on with fingers, pads and brushes, or blew it through a hollow bone so it sprayed around a hand or a shape.

We know the age because water running down the wall left a thin mineral crust over the paint. The crust can be dated, so the painting is at least that old.

715, one monk, one book.

For thousands of years after that, most pictures were painted by hand into a single copy of a single book. The Lindisfarne Gospels were made on Lindisfarne, an island off the north-east coast of England. Almost all of it was written and painted by one man, Eadfrith. It took an estimated five to ten years, and he may have died before it was done.

The pages are calfskin. One calf gave about four pages, so this book needed around 130 to 150 calves. A bigger Bible made nearby at the same time needed about 515.

The colours were ground from minerals and plants. Gold leaf was laid on a sticky base and rubbed until it shone. Red came from red lead, minium in Latin. The word miniature comes from it: it first meant painting with red lead in a manuscript, and only later came to mean something small. The best blue was lapis lazuli from one valley in Afghanistan.

1493, carve it once, print it thousands of times.

To print a picture you need something that can take ink again and again. The first answer was wood. Draw on a block, then cut away everything that should stay white. The lines are left standing, like a stamp. Roll ink over the block, press paper onto it, and only the raised lines print.

The block prints back to front, so the drawing goes on it back to front. Wood can't hold a very fine line, so woodcuts are bold. China got there first: the oldest dated printed book in the world, the Diamond Sutra from 868, opens with a printed picture.

Once a block existed, printers used it as often as they could. The Nuremberg Chronicle of 1493 has 1,809 pictures but only 645 blocks. The same city view was printed as Damascus, Ferrara, Milan and Mantua, with only the name changed. Between about 2,100 and 2,500 copies of the book were printed. Here is your block on the real page.

1665, lines finer than a hair.

The second way works the other way round. An engraver cuts grooves into a polished copper plate with a steel tool called a burin. Ink is rubbed into the grooves and the flat surface is wiped clean. A heavy roller press then pushes damp paper into the grooves, and the paper picks up the ink.

Grooves in copper can be much finer and closer together than ridges of wood, so engravers could shade with rows of tiny lines. But copper is soft. A plate gave a few hundred good prints before the lines wore down. It also needs its own press, so the picture usually went on a separate page from the text.

Robert Hooke drew what he saw through his microscope, and the drawings were engraved for his book Micrographia in 1665. The flea folds out to about 45 cm across. Samuel Pepys sat up until 2 a.m. with it and called it "the most ingenious book that ever I read in my life".

1796, nothing is cut at all.

Alois Senefelder was a playwright in Munich who couldn't afford to have his plays printed. Around 1796 he found a third way. Draw on smooth limestone with a greasy crayon. Wet the stone, and the water sits everywhere except on the grease. Roll on oily ink, and it sticks to the grease and slides off the water.

The artist could now draw straight onto the printing surface, so nobody had to copy the drawing into wood or metal. For colour, printers used one stone per colour, often 8 to 40 of them. Honoré Daumier drew news and politics this way in the 1830s. Toulouse-Lautrec drew posters in the 1890s.

1831, four people and two bowls of noodles.

In Japan a colour print took four trades. A publisher chose the subject and paid for everything. The artist, here Hokusai, drew it in ink. A carver glued the drawing face down onto cherry wood and cut through it, which destroyed the drawing. Then he cut one more block for every colour.

A printer brushed colour onto each block and rubbed the paper on by hand, one block at a time. A notch cut into the corner of every block kept the colours lined up.

The Great Wave blocks printed up to about 8,000 copies before they wore out. Each sold for about 16 mon, the price of two bowls of noodles. In 2023 one sold for $2.76 million.

1843, nineteen engravers, one picture.

Newspapers wanted pictures, but copper couldn't print next to words and ordinary woodcuts were too coarse. Thomas Bewick found the answer in the 1790s. He cut into the end grain of boxwood, which is hard enough for fine lines and can be locked into the same press as the type. One of his blocks printed more than 300,000 copies.

The Illustrated London News launched in 1842 with pictures on its pages every week. It sold 26,000 copies of its first issue and over 300,000 a week by 1863. Boxwood trunks are narrow, so a big picture was drawn across small blocks bolted together. The blocks were unbolted, handed to different engravers, and bolted back. At the end of 1842, Ebenezer Landells and 18 assistants cut one view of London on 60 blocks, working "day and night for two months". It was given away with the paper on 7 January 1843.

1880, a machine takes the engravers' job.

Every picture so far was copied by hand into wood, metal or stone. Halftone did the copying with a camera. A photograph is taken through a fine grid that breaks the picture into dots: big dots where it is dark, small dots where it is light. Acid etches the dots into a metal plate that prints alongside the type. From a normal distance your eye blends the dots back into greys.

The first halftone in a newspaper ran in New York on 4 March 1880. By about 1900 dots had almost completely replaced hand engraving in magazines and adverts. Nobody has counted how many engravers lost their work. One of them, Clemence Housman, was owed £100 in wages when her firm closed.

1916, the artist's own picture goes to print.

Halftone could print an artist's painting as it was painted, with nobody copying it in between. Magazines paid well for that. Scribner's paid N.C. Wyeth $2,500 for 17 Treasure Island paintings in 1911. The Saturday Evening Post paid Norman Rockwell $75 for his first cover in 1916 and sold about 2 million copies a week.

In 2013 one of his later Post covers, Saying Grace, sold at Sotheby's for $46 million.

1963, a drawing made of numbers.

At MIT, Ivan Sutherland wrote a program called Sketchpad and drew on a computer screen with a light pen. The computer didn't keep a picture of each line. It kept the two end points of the line as numbers, so a drawing could be moved, copied, resized and changed without being drawn again.

Vector drawing programs, like Adobe Illustrator from 1987, still store lines this way. Pen tablets, Photoshop in 1990 and the iPad brought drawing onto screens for everyone.

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