"His Kursi extends over the heavens and the earth."
The word 'Kursi' literally means 'footstool' yet the verse appears to give it a more in depth meaning. Why is this so?
Ibn Kathir expounds 'If the seven heavens and the seven heavens were flattened and laid side by side, they would not add up to the size of a ring in a desert, compared to the Kursi'.
Ibn Kathir further adds 'Kursi is the footstool and no one is able to give due consideration to [Allah's] Throne'.
(Tafsir Ibn Kathir, Vol 2, P 28-9)
Personal Comment: While no precise relation is given between the role, position, relevance, location, physical composition or purpose of the Kursi itself, the comparison is what is deemed to be important. To the human eye, the earth is vast and enormous and yet 'the known universe' is greater still with the additional cosmic masses of planets, moons, stars and galaxies and is the highest imaginable physical area known to us. But, in correlation with something small, tiny and insignificant in the realm of the Divine Kingdom, the Kursi, the world and the known universe as a combined unit in one size is like a ring in a desert; nothing in comparison.
If we further add the rest of the universe not yet discovered but known to exist, the word 'heavens' can now be employed. The sheer magnitude of the physical mass, area, volume of area and space is beyond human mathematical calculation, analysis or imagination. Yet the Kursi is still greater in physical length, width, height and total size in every way. In another context, the Kursi itself is also more important that the heavens and the earth combined, not just this but the Kursi itself is greater in prestige yet still insignificant; what then does that say of the heavens and the earth themselves.
Finally, the 'Kursi' itself is nothing in comparison to the 'Arsh' [the Divine Throne] itself, but since the verse does not include the word 'Arsh', why is Kursi used instead?
Kursi is the nearest highest sphere of imagination for the naked human eye and intelligence. Since the known universe is also the furthest possible point of travel available for the Jinn, we [the human race and the Jinn] can neither think, ponder, reflect or escape the area beyond it known as the heavens, the Kursi then is the only form of physical reality we can partially understand and comprehend. As such we can then recognise that we could never fully be able to know just how great, how large, how truly grand, how enormous and how majestic the Arsh is, just by measuring how miniature the Kursi is compared to it.