Thaumcraft has to be one of modded Minecraft's most influential magic mods, having 29 million downloads on only CurseForge and over 40 thousand comments on the original Minecraft Forum Thread at the time of writing this. With Thaumcraft now being discontinued, I think it is time to look over how we got here.
Thaumcraft 1 and 2
Despite the Minecraft Forum Thread only being from 2013, earlier versions of Thaumcraft existed. Almost every download is broken and even back then intermod conflicts where abundant. The oldest thread on the minecraft forums (and the oldest occurrence of thaumcraft that I could find) is back from December 2011, and it is littered with people complaining about compatibility issues. This was very common for mods back then, as IDs had to be shared between mods, and many mods directly changed minecraft itself instead of adding to it. While this old version had its compatibility issues like every other mod, it was still highly regarded and quickly gained a fan base, as it was unique and complex.
At this early stage, Thaumcraft had more in common with a more technomagical version of Project E / Equivalent Exchange than with today's Thaumcraft versions. It featured a magical crucible that could burn down items into energy, and a bunch of tools to use that magical energy, like symbols and runes, for primitive ritual-like machinery.
Thaumcraft 3 / Arcanacraft
Thaumcraft 3 was first announced with a new name and a new forum thread. Arcanacraft would be a complete rework and even multiplayer compatible! The new name was eventually dropped, but what stayed was the first version reminding us of modern thaumcraft.
Thaumcraft 3 would introduce wands, the (old) research system, golems and much more. Research was done by sacrificing items for their aspects in a research and guessing which aspects were needed for the yet unknown. Retroactively, this may sound like a stupid system, but back then Thaumcraft 3 was creative and somewhat groundbreaking.
Thaumcraft 4 and 5
Thaumcraft 4 as well as Thaumcraft 5 were in my opinion the most influential. With Minecraft Forge for 1.7.10 being the most supported version for years, many modpacks integrated Thaumcraft 4 in many different ways, and Thaumcraft 5 wasn't much of a difference, in content, as in influence.
Thaumcraft 6 broke with many things of Thaumcraft 5 and 4. It introduced new and completely different research, reworked auromancy and spellcasting and much more, but it still retained that Thaumcraft feeling and a lot of aspects from older versions. And that brings us to the last part:
The End of Thaumcraft
Thaumcraft was and is one of the most influential magic mods. Throughout its years, it has inspired many other mods, is a staple to tons of modpacks, and has whole modpacks like Blightfall based around it. But all good things have to come to an end. In 2019, Azanor announced he would stop modding due to not having enough time with work and studies. Since Thaumcraft is closed source, there is no easy way to port it to newer versions, other than just rewriting and violating intellectual property, so unless Azanor gives permissions to someone or comes back himself, there will be no Thaumcraft 7. There have been rumors that Azanor gave the source code to a new maintainer, however I couldn't confirm this, and until then we should be grateful for all the times we had and excited for what other mods may bring.