In todays media rich world it is hard to think of a situation when an illustration will convey brand new information to an audience. The only occasion that comes to mind in modern times is the use of court illustrations. For an entertaining collection of such images go here.
While watching a science documentary I was very impressed with the images created by Galileo Galilei . Famous for promoting the idea of the sun at the center of the solar system. His evidence was gathered using telescopes he built. With magnifications of between 20-32 times magnification he turned his attention to the moon and produced the first depictions of the moons surface. Until this the moon was considered to have a smooth surface. In his book "Sidereus Nuncius" translated to the romantic sounding "The Starry Messenger" he presented his accomplished illustrations.
Now let us review the observations made during the past two months, once more inviting the attention of all who are eager for true philosophy to the first steps of such important contemplations. Let us speak first of that surface of the moon which faces us, For greater clarity I distinguish two parts of this surface, a lighter and a darker; the lighter part seems to surround and to pervade the whole hemisphere, while the darker part discolors the moon's surface like a kind of cloud, and makes it appear covered with spots. Now those spots which are fairly dark and rather large are plain to everyone and have been seen throughout the ages; these I shall call the "large" or "ancient" spots, distinguishing them from others that are smaller in size but so numerous as to occur all over the lunar surface, and especially the lighter part. The latter spots had never been seen by anyone before me. From observations of these spots repeated many times I have been led to the opinion and conviction that the surface of the moon is not smooth, uniform, and precisely spherical as a great number of philosophers believe it (and the other heavenly bodies) to be, but is uneven, rough, and full of cavities and prominences, being not unlike the face of the earth, relieved by chains of mountains and deep valleys . . . .
Another article in Time explores Gallileo as an artist.