# If somebody could explain this [duplicate]

I have a doubt with preposition usage.

Why is it "at night" and "in evening/afternoon/".

If somebody could explain this exceptional case.

• @ScotM: Agreed on both counts. So I've put a bounty on the earlier At Night or In the Night?, and closevoted this one as a dup. Mar 11, 2015 at 0:44
– CAO
Mar 11, 2015 at 0:46
• Note that "in the night" is a legitimate construct (and there are places where it's the appropriate choice). It's just not the common choice. ("At evening", on the other hand, would not generally be used.) Mar 11, 2015 at 1:26
• As to why "at night", I might guess that, since one sleeps at night (and it's dark), any occurrence then "just happens", and it's coming and going is not observed and heralded. Thus night is regarded as a single indivisible entity, whereas afternoon and evening are continuous time ranges where "in" is appropriate. (But I could also guess that it's something like "at night" is of Nordic origin while "in the evening" is from French. Lots of such differences seem to arise from divergent etymologies.) Mar 11, 2015 at 1:32
• Or could it be due to the fact the night covers 2 dates?
– CAO
Mar 11, 2015 at 1:34

Of course, you could say "in the night", but not instead of "at night" - because they mean differently.

You could even say, "At the evening", rather than "in the evening". But they have different meanings.

At addresses the envelope of a concept.

In addresses a region within the envelope of a concept.

There are two mathematical games at play in the joust between in vs at

• Inside a set vs envelope of the set
• Event vs State

A state is the observable sustaining of a status of an entity.

An event is usually, but not necessarily, punctiliar. When an entity changes state, that boundary of change is an event.

"He died", "He started dying" are events. "He is dead", "He was alive", "He is dying" are states.

An event is indivisible. You cannot go and sit inside an event to observe it. You have to treat it as a singularity. So, you can only address the envelope of that singularity.

For example, "at noon", where noon is the singularity that delineates the state morning from the state afternoon.

However, sometimes you treat a sustained state as a singularity, and hence address its envelope, deliberately agnostic to what is in the envelope.

• At that evening, I had decided to no longer believe in a god who would vindictively send you to hell for your disbelief.
• At each morning, she would faithfully wait for her beloved but late master who would never return to the train station.

OTOH, sometimes you flip the paradigm because you wish to analyse inside the envelope.

• In the night, I would hear the silence broken by the scampers of pickup trucks. And then clanging of glass bottles hitting against metal chambers. And then the hushing of once a while rowdy celebration. In the night would be random sounds of running footsteps, and dogs barking. Even the coyotes contribute their share to the hushful commotion in the night. All for the sake of the tax-free moonshine sold under the counter and over the top across the valley.

"At the dawn of a new era" - You are addressing the envelope of an event.

"In the dawn of a new era, are old guards being executed, new dictators installed, old rules abandoned, new norms gradually shifting in, ..."

The use of prepositions, especially with expressions of time, does not usually follow logic but is simply idiomatic and has to be memorized on a case-by-case basis. The answey to questions like this is often, "Because that's the way native speakers say it."