Commentary on Meditations: B9:28

The recurrent cycles of the universe are the same, up and down, from eternity to eternity. And either the mind of the Whole has a specific impulse for each individual case - if so, you should welcome the result - or it had a single original impulse, from which all else follows in consequence: and why should you be anxious about that? The Whole is either a god - then all is well: or if purposeless - some sort of random arrangement of atoms or molecules - you should not be without purpose yourself.

In a moment the earth will cover us all. Then the earth too will change, and then further successive changes to infinity. One reflecting on these waves of change and transformation, and the speed of their flow, will hold all mortal things in contempt.

As often as the universe changes, much remains the same.  The ups and downs (change) are actually repetitive and constant.  Perhaps the length of those cycles have a long burn period and the relatively short life span of humans makes us think some of these changes are permanent, but in fact, there is far more lengthier repetition than we live to see.  As a side-note, consider the perspective of the Long Now Organization, which is running a project for the 10,000 year clock (also see youtube video below).  Life seen in this perspective gets at the heart of what Marcus means about the "recurrent cycles of the universe" and how they repeat for eternity.

Getting back to Marcus Aurelius and his thoughts about whether there is an impulse directing traffic, so-to-speak, or if there was just an original impulse behind the universe; this is the whole God or Atoms perspective, which has been and continues to be argued by many people, including philosophers.  For the Stoics, they believe whether one believes in God(s) or atoms (intelligent design or random events), what ultimately matters is your reaction to it all.  The Stoics believed that our actions should be the same irrespective if we believe in God or if we are atheist or if we are agnostic.  If we believe in intelligent design, then embrace it, welcome it and be grateful there is a rational mind directing traffic so-to-speak.  If we believe events are random (a sort of chaos), then we've learned that we still can eek out a life of reason and order, in which case we ought to live a life of purpose.

In the second half of Book 9 chapter 28, Marcus reminds us that we should have nothing but contempt (i.e. not worth our anxiety, worry and concern) for mortal things.  All things - you, me, others, our possessions, cities, countries, governments, cultures - pass in time.  Where we ought to place our concern, worries and anxiety is moral virtue.  As the Stoics succinctly say, "virtue is the sole good."

(see also Citadel p. 43, 148, 150-151, 161, 172)