Verily, knowledge is a lock and its key is the question. - Imam Ja'Far Al-Sadiq
Another great contribution to science of Imam Jafar al-Sadiq (A) was his Theory of Light. He said that light reflected by different objects comes to us, but only a part of the rays enter our eyes. That is the reason why we do not see distant objects clearly. - Infallible Imam (A) (www.alhassanain.org/english/?com=book&id=721)