[…] the relative pronouns are by far the most important of the connectives by which we bind together separate assertions, making a period out of what would otherwise be a loose aggregation of phrases.
- Whitney (1875), a pag.95

We have a verb, ‘be’, bearing the purely formal grammatical office of connecting a subject with its predicate. Such a connective is wanting in many languages, which are obliged simply to set the two elements side by side, leaving their relation to be supplied in the mind.
- Whitney (1875), a pag.90