The cornerstone today is usually called something on which a certain science is based or a certain postulate is based. But where did this well-known expression come from?
Turning to the Bible
Yes, yes, even if you are not at all religious, you do not need to wrinkle your nose. The fact is that the catch phrase "cornerstone" came precisely from the biblical texts. More precisely, it was the Bible that made the expression metaphorical. After all, before that, corner stones existed quite successfully, were used in everyday construction, and people did not endow them with any special honors. Where did the expression come from?
So, in the biblical texts, you can find the following phrase: "Jesus says to them: have you never read in the Scriptures: the stone that the builders rejected, the same became the head of the corner?" Literary historians and religious leaders agree that it was she who served as the beginning of the emergence of the stable expression "cornerstone".
Stone at the head of the corner
To understand what this mysterious expression means and what, in fact, Jesus taught, you need to understand the principles of the construction of buildings of those times. The fact is that the corners of buildings were not particularly able to erect at that time, and to create a foundation, large heavy stones with a structure and shape suitable precisely for placing them in a corner were required. After a long and difficult processing, a boulder of a suitable size was installed in the base of the building - this was considered the moment of laying. Needless to say, such stones were highly valued by the builders. On the cornerstone, as a rule, were written prayers of grace, the names of builders or architects, or praise to God. Among other things, he was the subject of some kind of cult and was revered as a shrine.
In the biblical story, which Jesus refers to, it is said about builders who carelessly abandoned the stone that interfered with them at the construction site. But when the time came, this particular cobblestone turned out to be the only suitable one and fit perfectly into the base of the house. If you do not go into the meaning and significance of the parable, we can conclude that the cornerstone is exactly what the whole building rests on.
The cornerstone these days
By the way, the cornerstones exist to this day; today they are given rather symbolic meaning. During the laying of buildings, commemorative plaques and inscriptions are placed on such stones, just as in ancient times. In some cases, a capsule with a message to future residents of the city is walled up in the foundation stone.