ON TO. We get _on_ a chair, _on_ an omnibus, _on_ a stump, and _on_ a spree, and not on _to_.
ONE. Certain pronouns of demonstrative signification are called indefinite because they refer to no particular subject. This is one of them. If we were putting a supposition by way of argument or illustration, we might say, "Suppose _I_ were to lose my way in a wood"; or, "Suppose _you_ were to lose your way in a wood"; or, "Suppose _one_ were to lose _one's_ way in a wood." All these forms are used, but, as a rule, the last is to be preferred. The first verges on egotism, and the second makes free with another's person, whereas the third is indifferent. "If _one's_ honesty were impeached, what should _one_ do?" is more courtly than to take either one's self or the person addressed for the example.
_One_ should be followed by _one_, and not by _he_. "The better acquainted _one_ is with any kind of rhetorical trick, the less liable _he_ is to be misled by it." Should be, "the less liable _one_ is to be misled by it."
In the phrase, "any of the little _ones_," _one_ is the numeral employed in the manner of a pronoun, by indicating something that has gone before, or, perhaps, has to come after. "I like peaches, but I must have a ripe _one_, or ripe _ones_."
Professor Bain says, in his "Composition Grammar":
"This pronoun continually lands writers in difficulties. English idiom requires that, when the pronoun has to be again referred to, it should be used itself a second time. The correct usage is shown by Pope: '_One_ may be ashamed to consume half _one's_ days in bringing sense and rhyme together.' It would be against idiom to say 'half _his_ days.'
"Still, the repetition of the pronoun is often felt to be heavy, and writers have recourse to various substitutions. Even an ear accustomed to the idiom can scarcely accept with unmixed pleasure this instance from Browning:
"'Alack! _one_ lies _oneself_ Even in the stating that _one's_ end was truth, Truth only, if _one_ states so much in words.'
"The representative 'I' or 'we' occasionally acts the part of 'one.' The following sentence presents a curious alternation of 'we' with 'one'--possibly not accidental (George Eliot): 'It's a desperately vexatious thing that, after all _one's_ reflections and quiet determinations, _we_ should be ruled by moods that _one_ can't calculate on beforehand.' By the use of 'we' here, a more pointed reference is suggested, while the vagueness actually remains.