When you get a picture in your mind's eye, like for example a green camel (there, you pictured it, didn't you!), it may seem quite ethereal and lacking substance, drowned out by your normal perception. But this inner universe is just as 'actual' as the physical world we live in, it is the substance of the mind, and understanding how the imagination works explains a lot about our psychological functioning.
There's a simple exercise you can do to demonstrate this mechanism of mind. Create an object in your mind, say a red sports car. Move it around, open the doors and sit inside it. Note that the more that you consider it to be in its own time stream, it persists. Think about something else, then go back to the car - it's still there.
Now go back to the time - just be at the same causative point - when you first created that car in your mind and put it there again, just as before. You'll find the car disappears - poof! Re-create the same time, space, form and event and things disappear, like they never were. (While you're at it, disappear the green camel too!).
This alternative universe of your own may seem intangible, but if you were in a flotation tank, with external senses nulled, the mind's creations would seem far more tangible, indeed as real as the physical universe, just as dreams seem completely real when you are immersed in them. Indeed, our physical reality may be considered a shared dream from which we have not yet awoken, but as inevitably as we awaken from sleep, we will awaken at the end of our life cycle, if not to some extent before - in the same way as we may sometimes become lucid in our dreams.
What is the significance of this? Our thoughts, decisions, intentions and so on are tangible in our mental environment and once created they persist unless viewed again exactly as is their true nature. If they are suppressed, for example because they conflict with other information or decisions that we have a vested interest in holding on to - because of needs and corresponding fears - this conflict continues, and although subconscious it holds some of our available attention.
You can try making an intention and then re-create it so it blows away. Or make a counter-intention - one that goes against the first - and notice that then they both persist. We all have a multitude of these intentions and counter-intentions, which layer and form structures. We may be happy enough, successful in life and healthy, but our true potential for awareness is limited by this smoke-screen of suppressed frustration - our self-knowledge is obscured by attachments to many conflicting views - and we may only vaguely realize this is going on.