Reason

The reason this tree fell is that it had rotted.

There is a reason why so many should be symmetrical: The selective advantage in a symmetrical complex is enjoyed by all the subunits[…]

He made reason with his boss about taking a day off.

The reason I robbed the bank was that I needed the money.

If you don't give me a reason to go with you, I won't.

This is the reason why he proposes to offer a libation, to atone for the abuse of the day by their diversions.

Ralph Touchett, for reasons best known to himself, had seen fit to say that Gilbert Osmond was not a good fellow[…]

I have forgotten the reason he gave for not travelling by air. I felt sure that it was not the correct reason, and that he suffered from a heart trouble which he kept to himself.

Mankind should develop reason above all other virtues.

The tremendous tragedy in which he had been involved - it was evident he was a fugitive from Weybridge - had driven him to the very verge of his reason.

And the specific distinction between man and beast is now, strictly speaking, no longer reason (the lumen naturale of the human animal) but science[…]

The [Isaac] Newton that emerges from the [unpublished] manuscripts is far from the popular image of a rational practitioner of cold and pure reason. The architect of modern science was himself not very modern. He was obsessed with alchemy.

16th century Edmund Spenser, Lines on his Promised Pension I was promised, on a time, To have reason for my rhyme.

[I]f two Quantities repreſented by the Numbers 20 and 4 be compared, by dividing the Antecedent 20 by the Conſequent 4, the Quotient is 5; but inverting the Terms, by dividing 4 by 20 the Quotient is #92;tfrac#123;4#125;#123;20#125;#61;#92;tfrac#123;1#125;#123;5#125;. By which Quotients are declared the Geometrical Reaſons of the propoſed Quantities, becauſe if the Quotient found be multiplied by the Conſequent, the Product is equal to the Antecedent; for in the former Compariſon 5#92;times4#61;20, in the latter #92;tfrac#123;1#125;#123;5#125;#92;times20#61;4; as Things again are referred to Equality.

"I had," said he, "come to an entirely erroneous conclusion which shows, my dear Watson, how dangerous it always is to reason from insufficient data. […]"

Still my spirit was not broken. I indulged the anticipation of escape, and that speedily. It was impossible, I reasoned, that men could be so unjust as to detain me as a slave, when the truth of my case was known.

“All right, Dad – I did follow you. But only because I was worried about you.” “Worried about me? I was worried about you! Hanging on to the roof of a speeding car! Are you nuts?” “It wasn’t moving when I climbed on to it,” reasoned the boy.

I reasoned the matter with my friend.

The talk was mainly between Aleck and Murdie, the others crowding eagerly about and putting in a word as they could. Murdie was reasoning good-humoredly, Aleck replying fiercely.

to reason one into a belief; to reason one out of his plan

That she was not immediately ready, Emma did suspect to arise from the state of her nerves; she had not yet possessed the instrument long enough to touch it without emotion; she must reason herself into the power of performance; and Emma could not but pity such feelings, whatever their origin, and could not but resolve never to expose them to her neighbour again.

to reason down a passion

to reason out the causes of the librations of the moon