The active perfect stem conjugation in Latin resembles the conjugation of esse a lot, but I recently learned that it is likely to be a coincidence. However, the active perfect indicative forms do not resemble esse — or any other Latin conjugation.

What is the origin of the personal endings (-i, -isti, -it, -imus, -istis, -erunt)? Do they come from the same place (PIE perfect, for example), or is it a collection of elements from a number of sources? There are familiar elements (-t in third person singular, -mus in first person plural, -tis in second person plural, -nt in third person plural), but the combination of all six is unlike other personal endings. There are also elements that are totally unexpected based on other Latin conjugation.

The active perfect stem conjugation in Latin resembles the conjugation of esse a lot, but I recently learned that it is likely to be a coincidence. However, the active perfect indicative forms do not resemble esse — or any other Latin conjugation.

What is the origin of the personal endings (-i, -isti, -it, -imus, -istis, -erunt/-ere)? Do they come from the same place (PIE perfect, for example), or is it a collection of elements from a number of sources? There are familiar elements (-t in third person singular, -mus in first person plural, -tis in second person plural, -nt in third person plural), but the combination of all six is unlike other personal endings. There are also elements that are totally unexpected based on other Latin conjugation.