Some linguistic processes or features derive their necessary appearance in all languages from the fact that languages are mediating systems and therefore reflect universals of human experience; thus the expression of moods of affirmation, command, doubt, desire for communion, or for any contingency in a linguistic category we can call ‘mood’ is only secondarily a linguistic universal. We must distinguish such universals [a] from those which may derive from some supposed innate, language-specific characteristics of man on the one hand [b], and those which derive from the physical nature of the medium on the other [c].
- Le Page (1977), a pag.233

Under [a] we must group echoisms, which furnish a limited number of language universals […].
- Le Page (1977), a pag.236