a being of the simplest essence’ ‘ The principle of

  The principle of ‘a being of the simplest essence’, basitulhaqiqah, is one of the most important one in transcendent philosophy upon which has been based the solution of many complicated and difficult problems. Now a question appears as: can the principle form a proof for the simplicity of the Necessary? In the paper, the principle has been analyzed and its background presented. Then it has been shown that the application of it for the purpose mentioned would lead to reasoning in circles. Finally a new explanation of the principle according to Sadra’s fundamental principles has been presented. Key words: simplest essence, all the things, Molla Sadra, simplicity, Necessary Being.