To see that we can think in several mental realms at once, consider the role of the word give in this simple sentence:
Mary gives Jack the kite.
We can see at least three distinct meanings here. First, we could represent the idea of the kite's motion through physical space by using a Trans-frame whose Trajectory begins at Mary's hand and ends at Jack's.
But quite beyond that realm of space, we also find a different significance in what Mary did — in another realm that we'll call
estates. This involves a different sense of give, in which the object need not actually move at all! Instead, what happens is the transfer of its ownership.
Each of us has an estate — the collection of possessions we control. And this realm of estate is more important than it might seem, because it lies between the realms of objects and ideas. In order to carry out our plans, it is not enough only to know what things or ideas are required and how to adapt them to our purposes. We must also be able to take possession of those objects or ideas, either by right or by might.
Possession plays essential roles in all our plans, because we can't use any materials, tools, or ideas until we gain control of them.
We can also interpret Mary's act within a social realm, in which we understand that giving gifts involves yet other kinds of relationships. No sooner do you hear of Mary's gift than certain parts of your mind become concerned with why she was so generous and how this involved her affections and obligations.
How can so many different thoughts proceed at the same time, without interfering with one another? I suspect that it is for the same reason that we have no trouble imagining an apple as both round and red at the same time: in that case, the processes for color and shape use agents that do not compete. Similarly, the different processes involved with ideas like give may operate in agencies so different that they rarely need to compete for the same resources.