What does 'it is enough that we know' mean?<br/>Is 'it' preparatory?<br/><a class='_ac _lb' lightbox='https://uat-englishforward-forums-backend.s3.us-west-2.amazonaws.com/2230227.0_rpqh5wxyxbsm.PNG '><img class='_ac _di img-fluid' style='width:526px; height:inherit; background: inherit;' data-delaysrc='https://uat-englishforward-forums-backend.s3.us-west-2.amazonaws.com/2230227.0_rpqh5wxyxbsm.PNG' src='https://uat-englishforward-forums-backend.s3.us-west-2.amazonaws.com/2230227.0_rpqh5wxyxbsm.PNG' /></a>