You answered your own question with the first quotation. Our real world as we think of it is a mere fantasy of ours which form is pretty much influenced by our culture and surroundings. You never perceive real world as it is, it always has a bit of your imagination so to say. Your culture can and does influence what you see and feel. As for imagination as a process of coming up with certain ideas that you do not really perceive them it is also a mix of reality (which is not reality as I mentioned before) and your own process of combining things you perceived before. Otherworldly, you will never imagine something that doesn't have its ground in your previous experience.