I have some problem with "at the expense of". Does<br/><br/><i><b>"light reveals itself at the expense of obscuring something else"</b></i><br/><br/>mean:<br/><br/>1. light reveals itself by lighting other things (because light itself has no physical presence and so is defined with its effects)?<br/><br/>or<br/><br/>2. light reveals itself by obscuring other things?