"Because I have seen a whole herd of black horses doesn't mean that all horses are black."

So here we are presented with the extended metaphor of Red Tinted Glasses. Alberto Knox uses a contrast between the actual world and a stained world as an example to show how perception nor reason cannot be fully trusted. Kant's view was that both ideas were "partly right and partly wrong."

Let me begin by defining these two ideas:
Empiricists "believed all knowledge of the world proceeded from the senses"
Rationalists "believed that the basis for all human knowledge lay in the mind," through reason

Kant's idea was that empiricists relied too much to their senses, and that rationalists "had almost forgotten the importance of experience."

Using the extended metaphor to align such, a empiricist would concluded that the world is red-based. That is only because if he looked through the red lenses all his life, all experiences he perceived will be a primary condition to form a red, complex conditional view of the world (Locke). Therefore it is arguable to say that the 'real' world will then be false, because it is out of what he normally sees. However, he has to be completely sure of himself that he has eliminated all other possibilities of the world - that is, he must be sure that what he sees is what everyone else sees, conforming it into an objective, primary quality. By that, the only achievable measure is by habit. Otherwise, his conclusion will be false as it would have been narrow-minded and becomes a secondary quality, which is subjective from people to people. Only if you know that every horse that existed is black can you say that horses must be black, albeit you must also be aware of the possibility of a white horse

Linking back to Kant's argument, it means that we cannot fully rely on our senses because whatever we perceive must be governed by the way we think. That is because 'habit' can only be true if it was to the same for each and every one on this planet. But clearly, that is not the case, because we are not clones of everyone and can think for ourselves. Therefore what we see becomes subjective. So why is it subjective? One, because we have free will to choose what to do; two, that is because we have different experiences in our lives, forming different stereotypes and prejudices, which can come from an individual or social context.

A point to prejudices and stereotypes are that they are thoughts due to misunderstandings and ignorance. If people learn to appreciate different cultures, then we will not be so narrow minded, and we will see the world much clearer and real. It is also morally correct too. That is because if we have accomplished to this state, we can then conclude that our senses are primary and accurate, whereby it is objective not subjective, and conforms to everyone. The world then will be what we see. That is why our emphasis on Global citizenship is so important.

In a rational view, we do not know if the world is actually red or not. Both are equally valid and false because we are part of the reasoning. Linking to that, we are part of the world we see, so we cannot tell whether we are red or not because it is us and many other elements that make up the world we perceive. Using the water in pitcher as an example, whereby water changes "shape" according to the shape of the pitcher freely, if we solely rely on our reasoning, then what we perceive will adapt to what we have thought about. That is to say our reasoning shrouds our perception. That is because if we have already possessed a value judgement on something whether or not we have experienced it, then what we perceive will be based on that judgement.

This danger of rationalism can be seen from Brutus in Julius Caesar. Though he was rational, his over-thought and misinterpretation let to the death of Caesar. Because he wrongly identified to himself that it was his civic duty to maintain Rome as a republic, he possessed no emotional consideration in his decision and clearly, did not consider what the people thought, eventually leading towards war and civil unrest for the next 40 years.

What that means is that a sole rationalist will wear "opaque glasses" (tributes to Laurence Wong) and see the world in a self-centred, sometimes against a social conventional, method.

So, the thing behind really is that Kant demonstrates how rationalism and empiricism both relate to each other. Your senses affect your thoughts, and your thoughts affect yours senses too.