In the metaphorical language of the old psychology, the threshold value, that is the strength or loudness of stimulus sufficient to make itself felt or heard, is less for the vegetative apparatus than for the brain.

The quantity of a syllable, whether long or short, does not depend on what is called the long or the short sound of a vowel or diphthong, or on a supposed distinction of accent as affecting vowels in some cases and consonants in others, but principally on the degree of energy or loudness with which the syllable is uttered, whereby a greater or less portion of time is employed.