Assume nothing. All you understand and have known to be so only exists momentarily and is subject to change without notice.
Assume nothing, the very ground beneath your feet, apparently solid and secure and immutable, is in fact filled with water which will rise to the surface turning streets to rivers in less time than it takes to make a cup of tea.
Assume nothing. All things are subject to change. The ground beneath your feet, usually so predictable and reliable, can be filled with rushing seismic energy which bucks and shakes the surface of the planet under you displacing energy that tears through you and everything else dissipating and leaving behind - amongst the after shocks and piles of brick - pulls and stretches in the warp and weft of everything.