But, while this muddy vesture of decay
Doth grossly close it in, we cannot hear it.
The Merchant of Venice, v. i. 54
The law of Seven is a law of vibrations. Just as in modern physics, this ancient idea considers the world to consist of vibrations, and this is a general law to help understand this, for practice use.
To increase the rate of vibrations of a material, we need to apply energy to it. E.g, to raise the temperature, you need to apply heat to a substance. In popular physics not much attention is given to the fact that the increase in the rate of vibrations is not always directy related to the rate of application of energy, i.e. applying energy at a constant rate does not always give a constant increase in the rate of vibrations. A very simple example is in heating water from ice to steam - there are two points, the point when the ice is at 0 degrees C, but not yet melted, and the point when the water is at 100 degrees C, but not yet steam. At these two points, one has to keep applying heat for a longer period of time for the temperature to rise...
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