This quote "Seeing is Believing" can be interpreted in different ways. Billions of people believe in God(s) that they have faith in. Can any of them "see" deities? A few claim they've seen Saints, highly-revered Nuns that have recently passed are claimed to be experienced by hundreds or thousands. These alleged events are merely anecdotal. Thousands can all agree on something they've experienced. There are explanations for that that run outside of this conversation. "Belief" is a very powerful thing. One need not be religious to have faith or belief in something. Faith in people, that their friend is going to be somewhere to meet with them for dinner requires faith or the belief that the friend will keep their word and not go to the titty bar instead. That "believing" cannot be seen, but is built on trust and/or habit. I might be getting "faith" and "belief" wrong. Are they not synonyms? I will research.

Blind at birth or later in life? If the blind have had many years of experiencing sight, then, they might be able to see visions from memory in their head. Can those born blind see visions in their head? I don't know. I don't assume those blind-at-birth cannot envision anything just because they've never seen the physical world. Much of how the brain functions and it's capabilities remain a mystery. How does a 40 year-old Savant know how to play Mozart on the piano while having the mental age of a child? They don't practice, read music (don't know theory, obviously) yet, the Savant can play such complicated music with seemingly little effort. It's rare, but these people do exist. A person that cannot do basic self-care tasks (e.g. cleaning their ass and all that) that normal people take for granted, but can play like a concert pianist without decades of study. There are some ideas neuroscientists are studying, but nothing nearing scientific theory (that I'm aware of).