How do we know, then, when a code's been cracked?when we are...

How do we know, then, when a code's been cracked?when we are right?when do we know if we have even received a message? Why, naturally, when, upon one set of substitutions, sense emerges like the outline under a rubbing; when a single tentative construal leads to several; when all the sullen letters of the code cry TEAM! after YEA! has been, by several hands, uncovered.