Literal Translation
It falls under the sense
Actual Meaning
It’s obvious, logical, it makes sense
Etymology
It was Blaise Pascal, “inventor” of, among many other things, the theorem that bears his name and atmospheric pressure (‘tomorrow’s pressure at sea level will be 1025 hectopascals’), who is believed to have coined this expression in the 17th century[1].
‘Tomber sous’ means ‘to present oneself’ (as in ‘tomber sous la main’, for example).
This expression was originally written as ‘tomber sous les sens’ to mean ‘to be directly perceived by the senses’, i.e. without the need to understand or learn it, thus conveying the obviousness of the thing.
Then, because it is necessary to show that one has common sense, it quickly evolved into the expression we use today, where “sense” refers to judgement or reason.
[1] Of course, Pascal did not actually “invent” atmospheric pressure, but he was the one who highlighted it, following Torricelli’s work, which is why his name is used as the unit of measurement for pressure.