A Breakthrough Sign is the stage where others start saying your meaning for you. Not because you paid them to, not because you gave them a script, but because the meaning is interesting enough; provocative enough, resonant enough; that it generates genuine coverage and conversation. "If you are a startup, you use Slack" is a Breakthrough Sign. Slack didn't say that. Other people started saying it. That shift; from "we say" to "others say"; is one of the most significant structural changes in the whole framework. The credibility of the meaning multiplies. Users who encounter the meaning from a trusted third party receive it differently than users who encounter it from the company itself. Conviction is easier to build when the validation comes from outside. At the Breakthrough Sign stage, the funnel symptoms largely resolve. Word of mouth happens organically. Awareness grows without paid spend. Users come in already more convinced because they heard about you from someone they trust. The exit to Symbol requires density: reaching the point where the meaning is so widely distributed that it becomes the default reference point for the category.