Comment by shagie
13 hours ago
It's avoiding two distinct vowel sounds in succession.
Consider other variations of this rule.
In French, one would say "l'hôpital" rather than "le hôpital" because the 'h' is an aspirated breath (try saying "a aspirated" rather than "an aspirated") leading to an initial vowel sound.
In Irish, the word for father is "athair". To say "her father" it becomes "a hathair" https://en.wikipedia.org/wiki/Prothesis_(linguistics)
In Turkish, it can be seen with araba (car). "I saw the car" -> "Arabayı gördüm." (note the 'y' to avoid two vowels). Book is kitap and "I saw the book" is "Kitabı gördüm." Which doesn't need the additional consonant sound between the final sound and the "ı".
Whatever language you speak, it likely has some form of this rule.
And other languages have the quirk too (like the "a unicorn" or "a university"). For example, in French there's l’hôtel and l'hôpital. But if you've got the hedge... it's la haie... or even more egregiously, the marmoset is le ouistiti.
> It's avoiding two distinct vowel sounds in succession
That implies that English added a consonant there to avoid double vowels, but it's the other way around: it used to have "n" always, same as other Germanic languages, and then it was dropped to avoid two consonants in a row