On Being the Right Size is a 1926 essay

Essay

An essay is a piece of writing which is often written from an author's personal point of view. Essays can consist of a number of elements, including: literary criticism, political manifestos, learned arguments, observations of daily life, recollections, and reflections of the author. The definition...

 by J. B. S. Haldane

J. B. S. Haldane

John Burdon Sanderson Haldane FRS , known as Jack , was a British-born geneticist and evolutionary biologist. A staunch Marxist, he was critical of Britain's role in the Suez Crisis, and chose to leave Oxford and moved to India and became an Indian citizen...

 which discusses proportions in the animal world and the essential link between the size of an animal and these systems an animal has for life.
It was published as one of Haldane's collected essays in Possible Worlds and Other Essays.

Thesis

Haldane's thesis is that sheer size very often defines what bodily equipment an animal must have:

"Insects, being so small, do not have oxygen-carrying bloodstreams. What little oxygen their cells require can be absorbed by simple diffusion of air through their bodies. But being larger means an animal must take on complicated oxygen pumping and distributing systems to reach all the cells."

Many of his examples are based on the square-cube law

Square-cube law

The square-cube law is a principle, drawn from the mathematics of proportion, that is applied in engineering and biomechanics. It was first demonstrated in 1638 in Galileo's Two New Sciences...

, although he does not use that terminology.

The bigger an animal gets, the more would they have to change their physical shape, but the weaker they would become.

Influence

This link became known to others as Haldane's principle, being referred to as such by urban planning

Urban planning

Urban planning incorporates areas such as economics, design, ecology, sociology, geography, law, political science, and statistics to guide and ensure the orderly development of settlements and communities....

 theorist Jane Jacobs

Jane Jacobs

Jane Jacobs, was an American-Canadian writer and activist with primary interest in communities and urban planning and decay. She is best known for The Death and Life of Great American Cities , a powerful critique of the urban renewal policies of the 1950s in the United States...

.

Another planning theorist, Christopher Alexander

Christopher Alexander

Christopher Wolfgang Alexander is a registered architect noted for his theories about design, and for more than 200 building projects in California, Japan, Mexico and around the world...

, refers to this principle in his theory of Independent Regions in A Pattern Language

A Pattern Language

A Pattern Language: Towns, Buildings, Construction is a 1977 book on architecture, urban design, and community livability. It was authored by Christopher Alexander, Sara Ishikawa and Murray Silverstein of the Center for Environmental Structure of Berkeley, California, with writing credits also to...

:

"...just as there is a best size for every animal, so the same is true for every human institution. In the Greek type of democracy all the citizens could listen to a series of orators and vote directly on questions of legislation. Hence their philosophers held that a small city was the largest possible democratic state..."

The conceptual metaphor to animal body complexity has been of use in energy economics and secession ideas.

External links

• On Being the Right Size - The text of the essay.
• On Being the Right Size - Another site for the text of the essay with fewer errors.