When to use "a" with "mirar"?

[Perikles]

Originally Posted by Luna Azul

Well, as I said before, the concept of "personal 'a' " is not real, so to speak.

True, but I think it is presented that way because when used for a direct object, it is not translated into another preposition, but just omitted, simply because the direct object doesn't need a preposition in English. I think I'm right in saying this also true for Romance languages generally, except Spanish and Portuguese.