The Spanish pronoun 'mí' (meaning 'me' when used as a stressed form, typically after prepositions) comes from the Latin dative pronoun 'mihi' meaning 'to/for me'. This Latin form was related to the nominative pronoun 'ego' meaning 'I'. Over time, the Latin 'mihi' simplified to 'mí' in Spanish, while retaining its use in prepositional phrases and stressed positions.

In Spanish, 'mí' is related to other first-person pronouns like 'me' (unstressed object pronoun) and 'yo' (subject pronoun meaning 'I'). While 'mí' is used after prepositions (like 'para mí' - 'for me'), 'me' is used as a direct or indirect object before verbs (like 'me gusta' - 'I like it'), and 'yo' is used as the subject of sentences.

The English pronoun 'I' is actually related to Spanish 'mí' through ancient Indo-European roots. While English 'I' comes from Germanic sources, both it and Latin 'ego' (which gave rise to Spanish 'mí') ultimately trace back to the same Proto-Indo-European root *egō/eǵh₂óm. This connection shows how even seemingly different pronouns like English 'I' and Spanish 'mí' can share deep historical ties.