There’s an English expression about people being an open book, meaning it is easy to know what they are thinking and feeling, and implying they are easy to get to know. Do you tend to find those people interesting as there’s so much to know about them, or uninteresting as there’s not much left to discover about them? Can someone be both? Interesting despite not much left to find out about them? I think so, if they were open, but still mysterious in their nature, metaphorically like in an unassembled puzzle or book which’s words you can read fully but which may not mean all that much to you together.
How I see someone being able to be very open, easy to read with lots of things known about them, yet still be intriguing, is in how well they can be understood. You might know all their behavioral tendencies, but you might not understand why, or vice-versa that you might know their mindset, but you can’t predict how it might manifest itself next. Now, I’m not suggesting anybody to go do this just to be an interesting open book type, though many celebrities do through procurement of their images to the world. I’m just saying that type of persona is the true, interesting open book persona, and one that needs a better name. Fortunately, the open book metaphor provided an easy lead to the persona name I used in the quote.
Among the many genres of books in existence, there is one where you have to understand how all the content of the book fit together to grasp it fully, not just read it. That’s like the persona I described, and that genre is the mystery. Hence, if you were going to be an open book, be a mystery!