The Mystery Solved by Mystery

 1.“An eye is meant to see things.
2. The soul is here for its own joy.

3. A head has one use: For loving a true love.
4. Feet: To chase after.

5. Love is for vanishing into the sky. The mind,
6. for learning what men have done and tried to do.

7. Mysteries are not to be solved: The eye goes blind
8. when it only wants to see why.

9. A lover is always accused of something.
10. But when he finds his love, whatever was lost
11. in the looking comes back completely changed.” 

A line that stands out to me, is when Rumi says, "Mysteries are not to be solved: The eye goes blind / when it only wants to see why."  First to dive into "Night and Sleep" you have background on Rumi.  The Muslim poet practiced  Sufism, in which the follower would give up worldly attachments to be closer to Allah, he also was  the founder of Whirling Dervishes. The poet lived in 13th century Persia. Now that Rumi's para dime is set the line can be dissected.

The definition of mystery plays a huge role in the meaning of the line.  Rumi is using the word mystery in a religious sense, as the rest of the poem is very Islamic.  When he writes "why" Rumi is talking about religious truths that men are not supposed to know. The poet is saying Muslims should not try to seek out the mysteries, or else their faith will not be the same. The devotion to Allah will suffer as a result.