Ketubot 28 - Childhood memories
An adult can testify in court about his childhood memories, and even though he would not be believed at the time when he saw these events, he is believed now. For example, one can say "I recognize the handwriting of my father, or teacher or brother, which I saw when I was young," and he would be believed in court.
Why do we need all three cases? - You might say that he knows his father's handwriting because he is always around his father, but not so for the teacher. Or you might say that he respected his teacher, and that is why the teacher's handwriting made a bigger impression on him - and so on - that is why we need to be told that all three testimonies are accepted.
But why in general do we believe him? Isn't this a money matter, and we have a rule that all money matters can be established only by the testimony of two adult witnesses; this one, however, was a minor when he saw the signatures? - In truth, confirming signatures is an idea of the Sages. Really we need people who remember the event of signing, and people are testifying about that, signatures being just the beginning of the testimony. The Sages thus were able to add a leniency to their own law.
In a similar vein one can testify about a woman that he saw her wedding, and she was coming with a veil and her hair down, as was customary of virgins. Thus, she is entitled to a larger Ketubah payment. Again, why do we believe this kind of a witness in money matters? - Most women do marry as virgins, and so his testimony is just revealing to the public that the court's decision is correct.
Art: The Young Bride By Alcide Theophile Robaudi