handmaiden
noun [ C ] uk/ˈhændˌmeɪ.dən/ us/ˈhændˌmeɪ.dən/
old use (also handmaid)女仆，侍女
a female servant
formal起辅助（或支持）作用的事物，基础
something, such as an idea, that helps and supports something else
Technique is the handmaiden of art. 技巧乃艺术之基础。