Vis (Thaumcraft 6)

Vis is a form of energy added by Thaumcraft 6. It is used in casting spells stored in foci or crafting items in the Arcane Workbench, which is the number displayed on the Workbench.

Getting Vis
Vis is naturally generated in your world, on a chunk-by-chunk basis. It is naturally regenerated with time. Vis regeneration can be accelerated with a Silverwood Tree.