Squareness of kanji characters


Is there, even if it's speculative, any explanation to the squareness of kanji
characters?

Why are 口, 回 or 円 not circles or round like の, for example?

Was making circles with early day tools too clumsy? If at the beginning they
had to scratch a hard surface, I can imagine that straight lines were easier
to draw.




> Was making circles with early day tools too clumsy?

Yes, exactly. Kanji derived from oracle bone script used in ancient China, and
it was indeed difficult to make circles on bones or turtle shells.

> ### [Oracle bone script](https://en.wikipedia.org/wiki/Oracle_bone_script)
>
> Oracle bone script (Chinese: 甲骨文) was the form of Chinese characters used on
> oracle bones—animal bones or turtle plastrons used in pyromantic
> divination—in the late 2nd millennium BC, and is the earliest known form of
> Chinese writing.
>
> * * *
>
> Comparing oracle bone script to both Shang and early Western Zhou period
> writing on bronzes, oracle bone script is clearly greatly simplified, and
> rounded forms are often converted to rectilinear ones; **this is thought to
> be due to the difficulty of engraving the hard, bony surfaces, compared with
> the ease of writing them in the wet clay of the molds the bronzes were cast
> from**.

After paper and brushes were invented, it was no longer difficult to make
rounded strokes, and various forms of [cursive
script](https://en.wikipedia.org/wiki/Cursive_script_\(East_Asia\)) evolved
(hiragana also derived from cursive kanji). Still, the "regular" form remained
full of straight lines and mildly-curved lines.

**EDIT:** As others say, the shapes changed significantly after people stopped
using bones and turtles, so what I have written above is a partial reason.

