"I" Why is it spelt with a capital letter?

[cornelia]

Dear Teacher,
I would like to get a plausibe and confirmed explanation of the spelling of
the pronoun "I" . Has it always been spelt with a capital letter and why?
Thanks in advance,
cornelia

[rewboss]

It hasn't always been spelled with a capital letter. I believe the capital letter came to be used when printing was invented. There is, I seem to remember, a technical reason for its use, but I can't remember it offhand. Something about the size of the letter, I think.

[cornelia]

Thanks for answering so fast.
Do you happen to know a reliable source which might be consulted?

[Casiopea]

Welcome, Cornelia.

From etymology online.com

I 12c. shortening of O.E. ic, first person sing. nom. pronoun, from P.Gmc. *ekan (cf. O.Fris. ik, O.N. ek, Norw. eg, Dan. jeg, O.H.G. ih, Ger. ich, Goth. ik), from PIE *ego(m) (cf. Skt. aham, Hitt. uk, L. ego, Gk. ego, Rus. ja). Reduced to i by 1137 in northern England, it began to be capitalized c.1250 to mark it as a distinct word and avoid misreading in handwritten manuscripts. The form ich or ik, especially before vowels, lingered in northern England until c.1400 and survived in southern dialects until 18c. The dot on the "small" letter -i- began to appear in 11c. L. manuscripts, to distinguish the letter from the stroke of another letter (such as -m- or -n-). Originally a diacritic, it was reduced to a dot with the introduction of Roman type fonts.

All the best.