There is a difference between knowing and seeing, as neurologist Oliver Sacks discovered when a patient suddenly lost the ability to see color. "The 'wrongness' of everything was disturbing," wrote Sacks, describing this man's false sight: what he knew to be true was not what he saw with his eyes.

And yet, we affix truth to sight so quickly, more than any other sense.

"The Kentish Hop Merchant and the Lecturer on Optics" by Scottish caricaturist Isaac Cruikshank in 1809. The scientist presents on the promising future of optics, the audience member, a Kentish landowner who undoubtedly grew hops for beer processing, mishears "Hop sticks." Learn more.

The bond between sight and truth was tested in 1610 when mathematician and amateur astronomer Galileo Galilei showed the world (through telescopic-inspired drawings) conventional wisdom of perfect heavens (fixed, unmoving, and unlike earth) was simply untrue.

In this short treatise I propose great things for inspection and contemplation by every explorer of Nature. Great, I say, because of the excellence of the things themselves, their newness, unheard of through the ages, and the instrument with the benefit of which they manifest themselves to our sight.
From Galileo's Sidereus Nuncius published in 1610.

"Look!" he might have shouted through the cobbled streets of Pisa, "I made these drawings based on what I saw through this tiny scope, and the moon has mountains! Jupiter has moons! Trust me; I made a drawing!"

 Galileo's drawing of the moon's mountains and plains as seen through his hand-made telescope and published in Galileo's "Sidereus Nuncius" in 1610.

The concept of heaven might have changed (eventually), but human reliance on sight to deliver truth remained uncontested.   What would have happened in science if we relied on other senses as much as sight to yield truth. Would we be able to feel the sun more honestly, more readily if we put more emphasis on touch? A tickle from our cosmic origins as if we had some skin amplifier in our toes? Read more about our love for the sense of touch. And as compelling as Galileo's drawings were, they were facsimile.

Imagine (someone must have asked at least once) if we could capture those mountains on paper! And show it to everyone through the years!

A photograph is a natural progression in optics, light, color, etc., but it was only with the advancement of chemistry that it became technically possible. In the 19th-century field of scientific polymaths, botanist Anna Atkins (March 16, 1799 – June 9, 1871) turned to photography to show her herbarium and ended up publishing the world's first photographic book.

Anna Atkins collected seed plants, supplied them to botanists at Kew Gardens, and donated them to the British Museum in 1865. Source: Natural History Museum.

In 1843 Atkins published what is now known as the first photographically-illustrated book: Photographs of British Algae: Cyanotype Impressions. Other editions followed in 1843 and 1853, featuring 411 plates arranged and labeled by Atkins.

Frontispiece for Photographs of British Algae: Cyanotype Impressions.

 Anna Atkin's Introduction to 'Photographs of British Algae: Cyanotype Impressions' by Anna Atkins.

A cyanotype works by brushing paper with photo-sensitive chemicals (ferric ammonium citrate and potassium ferricyanide) and then centering the object on top. The paper and object are then placed in light for 10 to 40 minutes, and while the paper turns blue, the area covered by the object remains white.

Therefore, the object - or its image - is the absence of light.

 Himanthalia lorea.

It's a plant but it returns us to this issue of sight and truth, for it is not a plant. It's the photographic absence of a plant.

Rather beautiful.

 Polysiphonia violacea.

 Cystoseira granulata.

 Sargassum Bacciferum.

A particular standout is Bangia fusco-purpurea, whose hair-like strands recall a mermaid's hair but which appears like a small bush aflame on the cyanotype. Atkins would have chosen how to display each of the 411 specimens and handwritten each of their scientific names.

 Bangia fusco-purpurea.

 Cystoseira ericoides.

 Laminaria saccharina.

 Cystoseira foeniculacea.

Sight might be fact, but it certainly isn't entirely truth, or truth entirely. Truth is eternally sought and unknown simultaneously, felt rather than seen, wider than the horizon, and higher than a tower of stacked dreams. Fact is what passes for truth while we pummel truth into something else. In her essays on the power, ethics and visual code of photography, Susan Sontag argues that photographs give people an “imaginary possession of a past that is unreal”. Exquisitely true.

Truth is also an issue for another day.

Edward Lear's nonsense illustration 'Tickia Orologica' from A Book of Nonsense published in 1861.

Back to Atkins and this revelatory body of work, a beautiful, innovative, practical use of cutting-edge science.

I am reminded of Virginia Woolf and her sly pondering about conditions necessary for creating art. Ultimately, you need to be in the room, in the process, and knowledgeable about the knowledge.

For women of the time, Atkins had unusual access to scientific knowledge. Although botany was generally more open to a woman (the genteel drawing of specimens encouraged), she received rare access to lectures through her father's position at the British Museum and Royal Societies. Atkins thus knew and studied the early inventors of the cyanotype process and the camera - inventors such as John Herschel and William Henry Fox Talbot.

 Anna Atkins, 1861.

Accompany Anna Atkin's beautiful creation and its impact on what people could retain and possess, Walt Whitman's harmony of nature and humans, written at the same time as Atkins was plating her botany collection; Susan Sontag's timeless essay on the culture and ethics of photography,  and a trip through Atkins' beloved Natural History Museum to see how the building and its collection have sparked wonder and curiosity for generations.

All images are from William Henry Fox Talbot's copy of Photographs of British Algae: Cyanotype Impressions courtesy of the Science Museum Group. Learn more.