Continuing Steps in Karate

In the last fortnight, I think I have seen people use a variant of the phrase "kata are the textbook of karate" at least a couple of dozen times.  It is a claim that instantly gets a lot of likes on social media and generally has a couple of follow-ups such as "kata contain all the techniques", "kata are the bible of karate" and "everything you need to know comes from the kata".  Which sounds great and seems like a justification of doing kata as the primary mode of training. But. How do kata transmit this knowledge?  How are they a textbook?  Without interpretation or guidance from someone or something that understands the context of each movement sequence, they teach nothing.  The teacher and ancillary training - especially with a partner  provide the context and the understanding. The kata is there to support  the learning that takes place, not provide the learning. This isn't my idea, by the way.  Patrick McCarthy talks about it

This post is related to, but is not a direct follow-on from the previous post on the original kata. In my school, and within its parent tradition, many of the kata have different variations.  For instance, in the kata Saifa, there are two different starts, two different ways to do the first section and two variants on the turn/sweep/hammerfist that are not only different from each other, but from other traditions as well.  Similar (accepted and taught) alternate variations exist in sanseru, shisochin, suparinpei, kururunfa, sepai, and seienchin.  Some of these kata have only one or two minor alternatives, others have more, with varying degrees of difference. Why? And what does it mean for understanding the origins and purpose of kata? There are obvious advantages pedagogically for teaching only one version of a kata, particularly to large groups of individuals.  Having a standard approach for everyone and every time makes it easier for the instructor to not only demonstrate to th