Context is crucial ! 
Lines
Let us now see an example – yes, right on your browser! Please look at Line-1 and Line-2, below. Do you derive the same meaning (that is, length, in this case) for Line-1 and Line-2?
Line-1 appears to be longer than Line-2...yet, they are really both the very same length – 160 pixels – independently of their appearing to be of different lengths.
Why do we derive the impression that Line-1 is longer than Line-2? The arrow pointers at the end of each line are responsible for what we experience, as we look as these two lines, however far from the mathematical "reality" (of the 160 pixels I have mentioned above) this experience is.
Thus our usually referring to this sort of experience as an optical illusion: we are aware of the fact that what we experience is illogical, at least from a mathematical viewpoint, that the meaning we derive is logically false! (More on this, and related topics, is available at MieNet's Illusion and Does your eye lie?....)
Nonetheless, experience is just about the only real thing which we, human beings can count on, in life, even though we like to appear, and to think of ourselves, too, as rational beings. Nothing is more real to each of us than that which we, each, experience, regardless of whatever inherent mathematical or logical truth. Experience, in turn, always takes place in context. Experience emerges out of the collection of contextual elements involved.
In the example above, the context for our experience of Line-1 and Line-2 is formed by the identical lines, themselves, along with the arrow pointers (equally identical – just placed in a symmetrically opposite way, at the ends of each line).
What do we conclude? Analogously to the case of a similar red traffic light, here, too, for two identical lines, the context within which each is immersed leads us to attribute each line a different length (or a different mathematical meaning).
The funny thing with Human perception is that, even now, that we know the lines bear the very same length, we look at them, and the experience (and meaning) we derive remains the very same: the lines do look different in length!
... Try taking a fresh look above, and see it for yourself!...
Once more, it is context that plays the essencial role regarding the different experiences we derive from each line: the lines are precisely the same, but appear different (i.e., evoke a different interpretation), as a direct result of the contexts that they are immersed in.
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