modernity is not continuity but change

I am scratching at something in the following three quotations: modernity; change, both social and existential; the phenomenological point called "the present."

Pierra Nora “The Tidal Wave of Memory”
“…the key feature of modernity is not continuity but change – an accelerated precipitation of all things into a swiftly retreating past. This change shattered the unity of historical time, that straightforward linearity which traditionally bound the present and the future to the past. For the way in which a society, nation, group or family envisaged its future traditionally determined what it needed to remember of the past. This gave meaning to the present, which linked the two. Broadly speaking, the future could be envisaged in one of three ways: as a form of restoration, as a form of progress, or as a form of revolution.

Friedrich Engels, “Socialism”
For everyday purposes we know and can say, e.g., whether an animal is alive or not. But, upon closer inquiry, we find that this is, in many cases, a very complex question, as the jurists know very well. They have cudgelled their brains in vain to discover a rational limit beyond which the killing of the child in its mother’s womb is murder. It is just as impossible to determine absolutely the moment of death, for physiology proves that death is not an instantaneous, momentary phenomenon, but a very protracted process.

In like manner, every organic being is every moment the same and not the same; every moment it assimilates matter supplied from without, and gets rid of other matter; every moment some cells of its body die and others build themselves anew; in a longer or shorter time the matter of its body is completely renewed, and is replaced by other molecules of matter, so that every organic being is always itself, and yet something other than itself.

Further, we find upon closer investigation that the two poles of an antithesis, positive and negative, e.g., are as inseparable as they are opposed, and that despite all their opposition, they mutually interpenetrate. And we find, in like manner, that cause and effect are conceptions which only hold good in their application to individual cases; but as soon as we consider the individual cases in their general connection with the universe as a whole, they run into each other, and they become confounded when we contemplate that universal action and reaction in which causes and effects are eternally changing places, so that what is effect here and now will be cause there and then, and vice versa.

Leo Charney, Empty Moments
In 1915, Alfred Wegener put forward the first version of what he called “drift theory” and what has come to be known as the theory of continental drift. “This is the starting point of displacement or drift theory,” wrote Wegener in the fourth edition of The Origin of Continents and Oceans. "The basic "obvious" presupposition common to permanence theory--that the relative position of the continents has never altered--must be wrong. The continents must have shifted.” In the words appropriated by Marshall Berman for the title of his seminal book on modernity, "Karl Marx defined modernity as 'all that is solid melts into air.' " Wegener sends us down a different but related path where we might say that in modernity all that is stable drifts into motion. Like Einstein’s image of elastic and relative time, Wegener’s vision of continental drift magnified in global terms the destabilizing of simple, stationary presence that marked modernity. (9)

modernity; time; memory; the present; phenomenology; Friedrich Engels; Alfred Wegener; Marshall Bermen; causality.