Instead of vowels, Hebrew invents the aleph, the not-quite-vowel, the first infinite sign and the zero, the non-entity. The aleph is a placeholder for silence into which a vowel must be inserted in order for the aleph, and indeed all the letters that follow, to explode into sound.

And if they shall not heed the voice of the first sign, they shall heed the voice of the last sign. (Exodus 4:8)

It is also the sign without a voice of its own, although it is the sign of the need for a voice.