Thus to the uncultivated mind a sudden thought seems like an audible announcement from without.

The superstitious man talks of being led by some good or evil spirit when new ideas arise in his mind or new resolutions shape themselves.

To the simple intelligence of the boor every thought presents itself as an analogue of an audible voice, and he commonly describes his rough musings as saying this and that to himself.
And this, mode of viewing the matter is reflected even, in the language of cultivated persons.

Thus we say, "The idea struck me," or "was borne in on me," "I was forced to do so and so," and so on, and in this manner we tend to assimilate internal to external mental phenomena.
Much the same thing shows itself in our customary modes of describing our internal feelings of pleasure and pain.

When a man in a state of mental depression speaks of having "a load" on his mind it is evident that he is interpreting a mental by help of an analogy to a bodily feeling.