The phrase "foundation stone" refers to the first block or stone that is placed at the base of a building. It symbolizes the beginning or starting point of the construction project. Full definition
It is the very foundation stone of the Christian life. (religion-online.org)
This work lays an important foundation stone for further studies on spatial signal perception by cells — both in yeast and in humans. (sciencedaily.com)
This tremendous feature is a gameplay foundation stone on which we can add and tune the realism level needed in nowadays game products, and racing game are especially affected by this need. (raylightgames.com)