Theory:

     “Of course he can sing it. Tansen can sing anything”. Akbar said. Tansen was afraid, but could not disobey the king. “Very well, my lord,” he said, “but give me time to prepare myself.” Tansen went home. He had never been more downcast and unhappy. “I can sing the Raga,” he told his wife, “but the heat it gives off will not only set the lamps alight, it will also burn me to ashes.”
 
     Then he had an idea. “If someone sings Raga Megh at the same time, and sings it properly, it will bring rain. Perhaps our daughter, Saraswati, and her friend, Rupvati, could do it,” he said.
Explanation:
  
Akbar, being a most significant fan of Tansen, accepted the challenge of Shaukat Mian very easily. He assured him that Tansen could sing anything. Akbar was very confident on Tansen's skill and asked him to sing Raga Deepak.
 
Akbar’s order.jpg
Akbar’s order
 
On hearing the king's order, Tansen got scared. Still, Tansen did not have any other option at that time. He accepted the king's order but requested some time to prepare for it. He returned home feeling sad and hopeless and spoke to his wife to explain Akbar's request on Raga Deepak. He told his wife that though he could sing Raga perfectly, the heat it gives off will not only set the lamps alight but would burn him to ashes.
 
Suddenly, Tansen had a thought on Raga Megh. The nature of Raga Megh is, it will bring rain in contrary to Raga Deepak. If he trains someone to sing Raga Megh simultaneously while he sings Raga Deepak, it will produce a counter effect. Tansen will be able to save himself by choosing this option. He had chosen his daughter Saraswati and her friend Rupvati to sing Raga Megh. Having decided so, Tansen felt a little relaxed for a while.
 
Meaning of difficult words:
  
S.No
Words
Meaning
1.
Gives off
To produce heat, light, smell, etc
2.
Downcast
Sad or upset without any hope
3.
Counter effect
An opposite effect 
4.
Perhaps
Used to refer possibility or uncertainty
Reference:
National Council of Educational Research and Training (2006). Tansen (pp. 15-19). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.