The trinity of "me, myself, and I" is well enough established to be the title of songs performed by Billie Holiday and Beyoncé Knowles as well as of a play by Edward Albee. Just to keep us straight on all this, Wikipedia has a disambiguation page on the phrase.
That we use these words every day doesn't mean we use them correctly, of course. One question that swirls around the nominative pronoun, "I," is, why it is always capitalized?
It's a fairly common online search. And what some of the discussion lacks in grammatical acumen, it compensates for in psychological insight:
"Hello, as a frenchie I just thought about this question about the I capitalized and I think English and American people have strong 'myself.' I mean, what is important in life? YOU, what you decide to do, to be, to love etc."
Another commenter on the same blog seemed to pick up that thread:
"The capital 'I' always reminds me of the english individualism. If only it was small, the world would have been a better place!"
Ah, if only!
"I" standing alone is such a little word to describe something that can be enormous: the ego. It's capitalized nowadays because it was once thought too little to hold its own on a page. As the Old English ic got whittled down to a single letter, writers and printers started capitalizing it to keep it from getting lost amid the bigger, pushier letters.
Myself, the middle sibling of this trio, is often used wrong. It's properly used in a reflexive sense ("I cut myself shaving") or as an intensifier: "I can do it myself."
In practice, though, myself is often used by people unsure whether to use "I" or "me" and/or reluctant to make themselves the subject of their own sentences: "The tour will be led by Professor Wigglesworth and myself."
If it's too much to say, "Professor Wigglesworth and I will lead the tour," one could at least say, "The tour will be led by Professor Wigglesworth and me."
Does anyone in real life actually say "It is I" anymore? Even English teachers and copy editors? Except in jest among friends to maintain their reputations as sticklers (perhaps)?
When you say, "It's me," you're expecting someone to recognize you simply by your voice. However many people you count on to do that, they're all pretty close to you. To use the formal "It is I" would be like crossing your own threshold and expecting a butler to announce you.
But the telephonic "This is he [or she] speaking," in response to a call from a stranger, lives on, in some quarters at least. By definition, it's a more formal context. One is more guarded. The stranger may have news that is not good.
We might learn from the French. Their language is in many ways so complex that their president made headlines a while back for getting a particular verb form right. But they have no problem using the equivalent of "It's me," and have been doing so at least since Louis XIV.
Of course they couldn't put their nominative pronoun, je, at the end of a sentence. It starts off with a high-energy consonant, but it ends with a weak little vowel. Je cries out to be the subject of a verb, and not the last word.
And so the French say, "C'est moi."
But that's enough about me.