The other two analogies for the fourth dimension I posted earlier stated why it is hard to understand the concept of fourth dimension, but this one is about how to understand the concept.
Take a piece of paper and a pencil and now we will start with the zero dimension or the non dimensional point, which does not exist practically and mark a dot on paper representing the zero dimension. Mark another such dot on the paper; we know duality, so "two" are always required to produce anything. Now draw a line joining these two zero or non dimensional points. Now this is the one dimensional line. Now drag this line to a certain distance, you will find a two dimensional plane, now assume to drag this plane upwards, this will result in formation of a three dimensional cube, so it was too easy up here. So we can see the line joining from one end to another increases the dimension. So what about the fourth dimension, you must be wondering how to drag this cube? To find this you may search it anywhere on the web "the four dimensional cube" but it is very confusing. I would try to illustrate in the easier manner.
Well, we know that fourth dimension is "Time". So make another assumption, you are at a point X, say, at 12.00 a.m. and after 5 minutes at 12.05 am you change your position and you are at some other point the point Y. Now draw the line joining these two points X and Y. This line is of time. If you see this line at one point of time that means you are seeing your whole movement between that particular interval of time between these two points at one instant of time.
Such cameras have already been developed and are used to observe the growth pattern of embryos of many species, which show the growth of an egg to a fully developed embryo, in a single frame. Amazing!
But, we should not forget time is not linear, but circular as everything is following a circular path, like moon revolves around the earth and earth around the Sun and so on. And that is how time is calculated. So time is circular. So if we assume the point X of our birth and point Y of our death and draw a line between these two points that come out a straight line but it can't be possible, as time is circular which clearly means that we are eternal but not with our physical body . As our physical body is made up of matter and that matter do completes its own time cycle after getting merged in to the five basic elements Earth, Water, Fire, Air, and Space. This is about our physical body, what about our own self. We got to complete our time cycle and we are the consciousness, we are nail of a wheel on which the whole wheel is rotating around and nail is just doing nothing (only witnessing). The whole universe is balanced by such nail which we call the supreme consciousness or Krishna consciousness or Shiva consciousness; we are the reflection of this universe. Many spiritual organizations like ISKCON (International Society For Krishna Consciousness) are working on this philosophy of Krishna Consciousness to awaken the slept souls, surprisingly western people look more interested in this movement rather than the Indians.
We are deluded by the wheel or the world (mithyajagat: illusionary world) and have forgotten about the real self, "nail" in this example. This is the inward journey towards the nail towards the consciousness. Once we follow this path and become one with that supreme consciousness or the Krishna consciousness we become God, the one who does nothing only "witnesses" or we can say God is like master of this time ring, the "Ringmaster". And salvation (Moksha) lies here.