Ravi was one of Sarkar's students, and I've mentioned this before in some of the mega-saeculum and political archetype threads.
Basically, Sarkar was trying to study what makes each saeculum different, and he also ends up focusing on four archetypes to demonstrate these differences. These archetypes are class/profession based, and they are all present in any given society at any given time, so what changes from saeculum to saeculum is which archetype is dominant.
Age of warriors (mega-high): Military order defends the borders of a newly defined nation, and works toward building infrastructure necessary for defense (roads, railroads, ports, fortresses).
Age of intellectuals (mega-awakening): Feeling safe and secure, society seeks higher meaning through art, science, and spirituality.
Age of acquisitors (mega-unraveling): As idealism becomes unsustainable, pragmatic realists manage the day-to-day operations of society - and pocket a nice bonus for themselves in the process.
Age of the commoner (mega-crisis): The rule of the acquisitors becomes inhumane as inequality skyrockets and human lives are treated as a mathematical min-max function with no purpose beyond maximizing profits. This era is brief and chaotic and destructive, but it gives rise to a new military order that better represents all levels of society.
Personally, I tend to think we're in the Age of Acquisitors, and in that context, 9-11 is perfect for the 4T start. "Go shopping" may not be the intellectual, military, or commoner's idea of dealing with a crisis, but it is the only thing acquisitors know. It would also explain why inequality has continued to grow through our 4T, in contrast with other 4Ts that feature reductions in inequality.