This is the Question, Charles Darwin writes at the top of the page. Each half of the page is a list brainstorming his two options with Emma Wedgewood:

To 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. — Forced to visit & receive relations 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.

or Not Marry?

No children, (no second life), no one to care for one in old age.— What is the use of working without sympathy from near & dear friends—who are near & dear friends to the old, except relatives

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 —

The final result:

Marry — Marry — Marry. Q.E.D.

He also goes on to wrestle with the question of marrying sooner vs. later. (via)

See also: lay it all out where you can look at it.