A check is not a check because it is written on a special kind of paper, a stock certificate is not a stock certificate because it is written on a sheet of paper of particular dimensions, similarly with all other kinds of securities — they are securities because they are treated by people as securities and issued by someone authorized to do that. A banknote — even perfectly printed, but produced by someone unauthorized — is not money, it is a counterfeit. A token is like a sheet of paper — you can write anything on it and it can become money or security or commodity by custom (later enforced by law).