Should you buy a new car? Should you drop out of college and pursue your lifelong dream of building your own business? Whenever faced with a difficult life choice, many people write down a list of pros and cons. Eventually, you might see things more objectively and reach a more rational decision. Many successful people employ this trick — including British naturalist Charles Darwin.

Darwin, the pioneering scientist whom we owe the theory of evolution, used a rational approach in most of his endeavors. He was a true scientist, after all. However, some people might find it odd to learn that Darwin actually used the same technique in his romantic life too.

Scribbling on the back of a letter from a friend, Darwin listed the pros and cons of marrying his cousin  Emma Wedgwood.  The original manuscripts are in the Darwin Archive in Cambridge University Library; these edited transcripts were originally published in Correspondence vol. 2, Appendix IV.

First note, after 7 April 1838

If not marry Travel. Europe, yes? America????

If I travel it must be exclusively geological United States, Mexico Depend upon health & vigour & how far I become Zoological

If I dont travel. — Work at transmission of Species — Microscope simplest forms of life — Geology. ?.oldest formations?? Some experiments — physiological observation on lower animals

B Live in London for where else possible[6] in small house, near Regents Park –keep horse –take Summer tours Collect specimens some line of Zoolog: Speculations of Geograph. range, & Geological general works. — Systematiz. — Study affinities.

If marry — means limited, Feel duty to work for money. London life, nothing but Society, no country, no tours, no large Zoolog. Collect. no books. Cambridge Professorship, either Geolog. or Zoolog. — comply with all above requisites — I could not systematiz zoologically so well. — But better than hybernating in country, & where? Better even than near London country house. — I could not indolently take country house & do nothing — Could I live in London like a prisoner? If I were moderately rich, I would live in London, with pretty big house & do as (B), but could I act thus with children & poor? No — Then where live in country near London; better, but great obstacles to science & poverty. Then Cambridge, better, but fish out of water, not being Professor & poverty. Then Cambridge Professorship, — & make best of it, do duty as such & work at spare times — ¶ My destiny will be Camb. Prof. or poor man; outskirts of London, some small Square &c: — & work as well as I can

I have so much more pleasure in direct observation, that I could not go on as Lyell does, correcting & adding up new information to old train & I do not see what line can be followed by man tied down to London. —

In country, experiment & observations on lower animals, — more space —

Second note, July 1838

This is the Question

Marry

Children—(if it Please God)  — Constant companion,
(& friend in old age) who will feel interested in one,—
object to be beloved & played with.— —better than a
dog anyhow.— Home, & someone to take care of
house— Charms of music & female chit-chat.— These
things good for one’s health.— but terrible loss of time. —

My God, it is intolerable to think of spending ones
whole life, like a neuter bee, working, working, &
nothing after all.— No, no won’t do.— Imagine living
all one’s day solitarily in smoky dirty London House.—
Only picture to yourself a nice soft wife on a sofa with
good fire, & books & music perhaps— Compare this
vision with the dingy reality of Grt. Marlbro’ St.

Not Marry

Freedom to go where one liked— choice of Society
& little of it. — Conversation of clever men at clubs—
Not forced to visit relatives, & to bend in every
trifle.— to have the expense & anxiety of children—
perhaps quarelling— Loss of time. — cannot read in
the Evenings— fatness & idleness— Anxiety &
responsibility— less money for books &c— if many
children forced to gain one’s bread.— (But then it is
very bad for ones health to work too much)

Perhaps my wife wont like London; then the sentence
is banishment & degradation into indolent, idle fool—

At long last, Darwin reached a conclusion: “Marry—Mary—Marry Q.E.D.” But only to move to the next important question.

“It being proved necessary to Marry — When? Soon or Late”

The Governor says soon for otherwise bad if one has children — one’s character is more flexible –one’s feelings more lively & if one does not marry soon, one misses so much good pure happiness. —

But then if I married tomorrow: there would be an infinity of trouble & expense in getting & furnishing a house, –fighting about no Society –morning calls –awkwardness –loss of time every day. (without one’s wife was an angel, & made one keep industrious). Then how should I manage all my business if I were obliged to go every day walking with my wife. — Eheu!! I never should know French, –or see the Continent –or go to America, or go up in a Balloon, or take solitary trip in Wales –poor slave. –you will be worse than a negro — And then horrid poverty, (without one’s wife was better than an angel & had money) — Never mind my boy — Cheer up — One cannot live this solitary life, with groggy old age, friendless & cold, & childless staring one in ones face, already beginning to wrinkle. — Never mind, trust to chance –keep a sharp look out — There is many a happy slave —

On November 11, 1838, 29-year-old Darwin wrote in his journal “The day of days!” after Emma accepted his marriage proposal. The two had ten children and remained together until Darwin’s death in 1882.