Why would scholars of Islam and Sufism ask for the meaning of thinking, hundreds of years ago? Perhaps this Hadith (Prophetic Narration) needed much explanation:

An hour of thinking is better than 60 years of worship, said the Prophet peace be upon him.

http://untiredwithloving.org/fikra_thinking.html

Today this Hadith will rarely be mentioned in the mosques, but way back when people heard it again and again and pondered upon its meaning.

Shabistari versed: Thinking is a voyage, to travel from Batil to Haqq.

Batil means anything other than Allah:

22:62, 31:30. Anna Allah Huwa (IT, He) Al-Haqq Wa(and/while) what you invoke besides Hu (IT, He) it Al-Batil

ذَٲلِكَ بِأَنَّ ٱللَّهَ هُوَ ٱلۡحَقُّ وَأَنَّ مَا يَدۡعُونَ مِن دُونِهِۦ هُوَ ٱلۡبَـٰطِلُ

For meaning of Haqq see:

http://untiredwithloving.org/haqiqa.html

Mufradat
Isfahani

The original meaning of Haqq is conformity or congruity similar to something mechanically/geometrically fitting another thing e.g. a hinge’s pin fitting into the hinge’s socket or cavity (Huqqa) in such a way that the door could swing around the hinge’s pin firmly, when placed into the socket or cavity (Huqqa).

Dara: Door’s utility characteristics functionality and usage are all directly linked to the said ‘conformity’ of the hinge’s pin to hinge’s socket. Without this conformity the door ceases and its functionality and utility of swinging to open/close desist.

Irfan: All that which is from Allah is Haqq (Valid) and all that which is not from Allah i.e. from other than Allah is Batil (Invalid). 

Batil produces nothing, engineers nothing, endeavors nothing, while Haqq gives everything its functionality and originates things into being:

34:49. Say: Came Al-Haqq and Al-Batil made nothing and reinstated nothing

قُلۡ جَآءَ ٱلۡحَقُّ وَمَا يُبۡدِئُ ٱلۡبَـٰطِلُ وَمَا يُعِيدُ

 

In conclusion Shabistari says: One sure bet to voyage towards Allah is via thinking! And to find new things and bring things to fruition and reinstate them is by Haqq and voyaqe to Haqq is thinking.