In a scant few days, it'll be 1 score years ago since September 11th, 2001 - a day that would live in infamy. What do we know about the history of the lead-up to the event? How did the ideation thereof emerge? What were the goals stated at different levels of privacy and publicity (such as it was), of individuals, ingroups, and outgroups, and what justifications were put forward, and why were they accepted? Who chose to support the project, be it with political capital, money, their life, etc, or just their silence, how were they in a material position to do so and in the appropriate headspace as well, knowing the certain and the likely consequences, for them and their loved ones and many, many innocent bystanders?

In short, why did this catastrophic event happen? Why then, rather than earlier or later? Why that target in that country?

I'm asking this question from a broad historical perspective and with particular interest in the politics, ideology, and economy involved.

The logistical details and minutiae of the plan's implementation (and the US Intelligence agencies' failure to prevent it) have been the focus of a lot of media on the matter, but they may be obscuring the forest for the trees. I think we'd all like to understand the context behind it. Make sense of the senselessness. Can any of you brave historians out there help us?