The thing with everything, is that all we can imagine about it, is true. But everything we cannot imagine about it, is also true.
Our ability to reason, think and contemplate is just one of our senses. And like all others, it is a sense bound to our local reality, and therefore limited by it. As our eyes observe light, our mind observes the fathomable.
And for all beauty our other senses could ever make us feel, the fathomable has the potential to be more beautiful still. For the fathomable is not bound to our reality and can give us a glimpse of what might lie beyond. This is the reason existence can only be explored by the mind. This is the reason we should want to explore with the mind.
I believe our perception of the fathomable can grow as we grow. But as we are bound to our senses and eventually by our reality, the fathomable will also be bound. We can reach out and try to understand within those boundaries. But to go beyond is impossible by its very definition. The fathomable will always be a limited part of everything, mirrored by an unending sea of the unfathomable.
Like a character in a story could never observe the book he is written in, we could never observe, or even fathom the concept of everything.