What is Thirteen Emptinesses 十三虚无?

Thirteen Emptinesses are thirteen health-preserving essentials advocated by Taoism, namely: Xu (Emptiness), Wu (Nothingness), Qing (Purity), Jing (Tranquility), Wei (Subtlety), Gua (Simplicity), Rou (Gentleness), Ruo (Weakness), Bei (Humility), Sun (Reduction), Shi (Timeliness), He (Harmony), and Se (Frugality).

To discard the form and forget the body, remaining serene as if non-existent, is called "Xu (Emptiness)";
To diminish the mind and abandon intentions, abolish falseness and rid of desires, is called "Wu (Nothingness)";
To concentrate the essence and accumulate the spirit, not mingling with external things, is called "Qing (Purity)";
To revert the spirit and ingest vital energy, staying calm without movement, is called "Jing (Tranquility)";
To reside in seclusion and live in leisure, with neither fame nor merit displayed, is called "Wei (Subtlety)";
To leave one's wife and children, wandering alone with the Dao, is called "Gua (Simplicity)";
To breathe in balance, with the breath smooth, moist, delicate and slight, is called "Rou (Gentleness)";

To soothe the form and follow the body, attending to all matters, is called "Ruo (Weakness)";
To detest honor and glory, finding contentment in poverty and joy in humiliation, is called "Bei (Humility)";
To shun fullness and escape abundance, with food, clothing and lodging kept simple, is called "Sun (Reduction)";
To sit quietly following the yang energy, adapting to changes and repelling evil, is called "Shi (Timeliness)";
To be neither hungry nor thirsty, neither cold nor hot, neither happy nor angry, neither sad nor joyful, neither swift nor slow, is called "He (Harmony)";
To cherish one's sight and hearing, words and thoughts, keeping them firm without waste, and retaining the spirit internally, is called "Se (Frugality)".