That is a neat experiment!
By the way, you can use the categories parameter to tell catlist to use the categories defined at a tiddler other than the one you're looking at. So, if the categories are supposed to be the same throughout all, e.g. Centuries, you can simply define them there and say...
<<catlist categories:Centuries>>
If you always want to show a catlist for all centturies, i.e. tiddlers matching a filter, use this method:
For example, you could create...
title: Centuries
catlist: Events Groups Ideas Institutions People ByLocation
<<list-links filter:"[all[current]tagging[]sort[]]">>
...and tag all centuries Centuries.
Then create a conditional ViewTemplate section...
title: $:/.history/ui/ViewTemplate/catlists
tags: $:/tags/ViewTemplate
list-after: $:/core/ui/ViewTemplate/body
<$list
filter="[all[current]tag[Centuries]]">
<<catlist categories:Centuries>>
</$list><$list
filter="[all[current]tag[SomeOtherTopic]]">
<<catlist categories:SomeOtherTopic>>
</$list>
Now you can remove all the catlist fields and special markup from your century tiddlers and you are sure to always see the same category listing throughout all centuries without having to set the catlist field for each and every.
I also like to use a summary field at tiddlers for use in lists, e.g.
example: same tiddler
and then...
...rather than a plain tagging list, e.g. in the Centuries tiddler,
so as to show a summary for each century along with just the name.
Best wishes, Tobias.