If the inputs to a system cause the same pattern of activity to occur repeatedly, the set of active elements constituting that pattern will become increasingly strongly inter-associated. That is, each element will tend to turn on every other element and (with negative weights) to turn off the elements that do not form part of the pattern. To put it another way, the pattern as a whole will become 'auto-associated'. We may call a learned (auto-associated) pattern an engram.
The tai chi master was delighted after three years of training that his student was able to replicate the tai chi forms he had been taught. He told the student to go away and practice by himself for a further three years and then return. After three years the student returned, crestfallen and confessed that even while practicing diligently, he had lost 30% of what his teacher had taught. The teacher was disappointed and sent the student away to practice for another three years. Three years later the student returned and said he had lost 60% of his learnings. Once more the teacher sent him away to practice for three more years. On his return the student told the teacher he had now lost 100% of his learnings, at which point the teacher congratulated him as he had made the art his own.