The Articles in Tao-te Ching of Lao-tsu about Ki
"Tao-te Ching" means the bible of Tao and benefit, and it is a bible of Taoism. So you can expect many articles about Ki in it. But there are only three chapters that contains the word "Ki".
The Tao-te Ching explains Ki from two kinds of viewpoints;
one is Ki as vital energy of man and the other is as the energy of the cosmos
that constitutes everything. The chapter 10 and 55 stand on the first prospective,
and chapter 42 on the second view.