press your tongue against the heaven of your mouth

This is the story of how I bought a mouthguard and how it made me think about the history of language and thought. On a beautiful sunny day and I went for lunch and swung by a sports shop and got one. Back at home I started reading the instructions on the package. I read the one in English first:

Bring water to a boil. Remove water from heat source. Place mouthguard in the water for 12 seconds (see picture).

After that you have to put the mouth guard in and let it adjust to the shape of your teeth. In that bit it says:

Press your tongue against the roof of your mouth.

and in Spanish:

Empuje la lengua contra el cielo de la boca.

Cielo de la boca! Roof of the mouth! Only that 'cielo' doesn't mean roof, it means heaven. Heaven of the mouth. The firmament of your mouth.

Of course, heaven was something quite different before. It was the roof of our world, a solid surface encrusted with stars, a protective shell that enveloped our planet and gave the sun and the moon a place to run around and around again and come back on the other side.


from some random website:

Until about the time of Sir Isaac Newton (1642-1727) [See biography], Christian scholars understood the firmament of the Bible as depicting the rigid sky, which revolved around the earth once each day, carrying along all the stars. This assumed motion of the sky reflected the common-sense notion that the earth was stationary. For the stars to move in a manner consistent with observation, they had to be held fixed in their relative positions. The stars seemed to trace partial circles around the poles each night. Their movements appeared exactly as if they were fixed on the underside of a great revolving dome, or the inner surface of a sphere. This belief in a rigid sphere of heaven gave rise to the expression "the sphere of the fixed stars."

The planetary motions did not conform to this explanation, and it was the detailed study of the orbits of the planets by Johannes Kepler, his discovery of the elliptical form of the orbit of Mars, and Newton's interpretation of Kepler's discoveries, which led to the recognition of the law of gravity, and the abandonment of the idea of a rigid rotating firmament.