For they err not only by adding attributes after whose removal the sun would still exist, eg 'going round the earth' or 'night hidden' (for from their view it follows that if it stands still or is visible, it will no longer be the sun; but it is strange if this is so; for 'the sun' means a certain substance); but also by the mention of attributes which can belong to another subject; eg if another thing with the stated attributes comes into existence, clearly it will be a sun; the formula therefore is general.