Fifth comparison or upamāna: An echo (pratiśrutkā)

In a narrow valley, a deep gorge or an empty house, when a sound (śabda) or a noise is made, from this sound [that is produced] another sound arises that is called an echo. The ignorant person thinks that there is somebody who is repeating his words, but the wise person knows that the echo is not due to a third person and that it is solely by a reverberation of the sound (śabdasparśa) that there is a new sound called an echo. The echo is empty (śūnya) of reality but it is able to deceive the ear organ (śrotrendriya). In the same way, when a person is about to speak, there is a wind (vāyu) in his mouth (mukha) called Yeou t’o na (udāna) that passes to the nostrils (nābhi); when it strikes the nostrils, an echo is produced and at the moment that it comes out, it strikes in seven places and subsides. That is language (abhilāpa). Some stanzas say:

The wind called udāna
Strikes the nostrils and rises up;
This wind then strikes in seven places:
The nape of the neck, the gums, the teeth and the lips,

The tongue, the throat and the chest.
Thus language is produced.
The fool does not understand that;
Hesitant, obstinate, he produces dveśa and moha.

The person endowed with wisdom
Is not worried, does not cling,
And does not commit any mistake;
He adheres solely to the [true] nature of dharmas.

Bending and staying straight, bending and straightening up,
[The sound] that comes and goes manifests the language.
There is no agent there.
This [language] is a magic show.

How would anyone know
That this skeleton, this bundle of nerves,
Would be able to produce language
Like molten metal ejects water?

[103b] This is why the bodhisattvas regard dharmas as an echo.