Let's use the famous "Flatland" analogy.
Imagine a world where everything is 2D.A world inhabited by 2D shapes.A world we'll call "Flatland".
Here,we'd have squares,circles,triangles,etc. Remember,2D has no depth,so our world would have no depth.We would only be able to see 'around us' and not 'above' or 'below' because for 2D beings,the concept of depth is non-existent.

Are you still with me?

Suppose one day an apple fell from no where and landed on Flatland,how would the inhabitants of Flatland view this apple?[Remember,apples are 3D]

To illustrate how they'd see it,take an apple and place it on an inkpad.Then take the stained apple and place it on white paper.The impression it makes would be the way 2D people would see it,more or less,a shadow.

Which brings me to a point I made earlier.Even though the apple exists,the 2D objects can't see it though they can feel its presence.By extension Man can't see into 4D,though it exists.

Don't be baffled,the best part is yet to come.Keep following to find out...