The Black line represents the optimism of people about life in general based on what I see in expressions of art. It never reached levels in the early Renaisance that were reached in the time preceeding the rise of Greek culture.
Purple is art. I give its zenith as the self portrait of Albrecht Durer ca.1500. Afterwards things tend to get "baroque" . One of Leonardo's angels has the "Archaic smile" around this period. That smile represents the next to high point in a civilizations' rise. The current muck of twentieth century junk, glob & smear art has worn so thin that it could be replaced by almost anything anytime. Just look at the Vietnam war memorial statue and you say "This ought properly to replace the junk." It will. Wait 'n see.
The Blue line represents politics which by most accounts must have its zenith in the late eighteenth century (expressed by the American Declaration of Independence). It has been going down ever since and no men of stature in this realm are presently visible.
Red is physics. It reached its high water mark in the last century. It has been going down since and nearly terminates in the swamp of late twentieth century "name games" and the quest for bigger machines to do the work intended for a mind. (Despite claims to the contrary, the super conducting super collider was a cudgel with which to 'beat' the truth out of nature. A false hope since no machine generates knowledge . . . only data. I was sorry to see it dismantled because the defeat was seen as a victory over science rather than a victory for science.) This subject is nearly deceased.
Gray is for mathematics which has its high water mark in Gauss and Euler as well as others of that era. In the twentieth century, research mathematicians have no longer any idea of the fundamentals of their craft and have accepted extended computer solutions to historic questions in lieu of answers of appropriate scale.
Gray also fits well with music (Bach, Beethoven, Brahms). It has declined to absolute zero in the form of "rat" music (music that sounds like a rat running over a keyboard).
Light Blue is for heavy industry. This area is on the way down. Because it is the base upon which technology (Yellow) rests, technology is doomed though presently it is meteoric in its rise. Medical knowledge (White) is also rising but rests on technology. So it will tumble soon enough as well.
I would expect of course, to get many an argument about this and I have not tried to be very accurate. My main thesis is that civilization has been deteriorating despite its apparent ability to cope with physical existence.
An element of civilization which has collapsed loses its ability to influence. It wears paper thin and is ready for replacement. The new element then starts its way up again. This process will repeat until history comes to an end.
By "failsafe" I mean, we are presently decaying but things may well turn around if we but put forth the effort.
Sufficient data has been collected by man.