This article is a historical study on the distinction between to-infinitives and bare infinitives. Generally, the to-infinitive denotes the futuristic, indirect potential event, while the bare infinitive denotes the direct one. This meaning distinction between the two infinitival constructions has been persistent through the long history of English, as argued in Fischer(1995, 1996a, 1996b, 1997a, 1997b, 2000). The issue is how and from what this meaning difference is derived. The common account is structural, saying that the to-infinitive has the clausal status such as IP or CP with the inflectional element inside, while the bare-infinitive has the small clause structure such as VP. This account assumes that the infinitival marker to is a meaningless grammatical element(INFL). However, it is argued in this article that the infinitival to is a lexical element having its own lexical meanings and that these lexical meanings of the to are the maintenance of its original prepositional characters. In other words, the lexical meanings of the infinitival to, derived from its original prepositional category, has not been wiped out, although the meanings were a little weakened in ME for a while. The conclusion is that the meanings of the to-infinitives such as futurity and indirectness are due to the morpheme to itself, not to the structure caused by its presence.