The knowledge which Mary had while still on earth had limits, especially at the beginning. She did not, for example, understand the full import of what Jesus said about His Father’s business when she found Him in the Temple. But, as has been often said, the limits were limits, not gaps. Hence she was in no sense ignorant, for the limits did not deprive her of the knowledge of anything she should have known at the time. God’s Mother knew at every stage of her life all that it was becoming for her to know.
Nor was she subject to error. She was never precipitate in judging; if she had not sufficient light she suspended her judgement; if she was not sure about a thing she was satisfied to affirm that it was likely or probable. For example, when she thought it likely that Jesus was not in the company of her friends and relatives on the occasion when she lost Him, her belief was a very likely one indeed—though in point of fact it was not true—and in looking on it as likely Mary did not err.