Believe it or not, a "secret" society refers to the secrets they hold, not that the society itself is secret. The Masons are public about their existence (if quiet) but their inner "rites and rituals" are secret.
Duncans Ceremonies is the most famous revelation of Masonic secrets, but no dues-card and not being 'in the book', ultimately counts for nothing, as you won't even be able to properly converse with a mason, nor enter a lodge, without either.