The legend of Cang Jie

That's interesting. 文 is like "alphabets", and 字 is the compound words. It's easier for me to understand that a-Z is 文, and all the English words are 字. In Chinese, all the radicals and strokes are 文, and the characters are 字 (methinks). It's understood that that some 文 and 字 are the same.

黄帝 时代，国家 疆土 扩大，各地 老百姓 的 来往 不断 增加，其中 包括 互相 做 生意。开始 时 用 在 绳子 上 打结 的 方法 来 记帐：用 每个 结 代表 一件 东西，例如 一头 牛、一头 羊 等等。满 十 就 打 一个 大圈。
这个 方法 很 麻烦，而且 由于 记帐 的 绳子 会 烂掉，被 老鼠 啃坏，就 引起 很多 纠纷，天下 的 事情 又 开始 乱纷纷 起来。
于是 黄帝 命令 一个 叫 苍颉 的 官员 去 制造 文字。苍颉 仔细地 观察 天上 的 太阳、月亮 和 云彩，地上 的 植物、裂缝 和 鸟兽 的 脚印，制造出了 许多 基本的 文字 符号，因为 来源于“花纹”，所以 就 把 这些 基本 符号 称为“文”。他 又根据 这些 基本 符号 的 组合 制造了 许多 复合 的 文字 符号，因为 是 从“文”的 基础 上 产生 的，就 好像 是“文”生下来 的 孩子，所以 就 用 房子 下面 的 一个“子”来 代表 这些 复合 符号，就是“字”。
苍颉造出了文字之后，天下又太平了。

It was the Huang Di era,the country's territory expanded,communication with people from all over the place increased,and among those was doing business with others.they began to use ropes to calucate things; and used every knot to represent something,for example a cow and a sheep etc.If it reached ten then they would tie a big knot.This technique was frustrating,and plus the rope could fall apart,or knawed on by mice,and that lead to a lot of trouble,and the earth, once again, was becoming very chaotic.So Huang Di ordered an official by the name of Cang Jie to create "characters."Cang Jie carefully observed the sun, moon, and clouds,the earth's plants, dirt cracks, and animals' footprints,and created a lot of basic character symbols,because it came from "Hua Wen,"so he called these basic symbols "wen" (文).He also followed the basic characters' assembly to create plenty of compound symbols,because it came from "wen,"it was like a child being born from "wen,"so he used the "zi" (son 子) under "house" to represent these compound symbols,so it became "zi" (字).After Cang Jie created these characters,the earth was once again a peaceful place.