What inhibits us to understand the reality of things.  Is it lack of knowledge, is it lack of intellect or is it something else.  Following are some of the things that Quran mentions that inhibit our ability to understand true nature of things.

1: Arrogance

وَلَقَدْ آتَيْنَا مُوسٰى الْكِتَابَ وَقَفَّيْنَا مِن بَعْدِهِ بِالرُّسُلِ وَآتَيْنَا عِيسَى ابْنَ مَرْيَمَ الْبَيِّنَاتِ وَأَيَّدْنَاهُ بِرُوحِ الْقُدُسِ أَفَكُلَّمَا جَاءكُمْ رَسُولٌ بِمَا لاَ تَهْوَى أَنفُسُكُمُ اسْتَكْبَرْتُمْ فَفَرِيقاً كَذَّبْتُمْ وَفَرِيقاً تَقْتُلُونَ

And verily We gave unto Moses the Scripture and We caused a train of messengers to follow after him, and We gave unto Jesus, son of Mary, clear proofs (of Allah’s sovereignty), and We supported him with the Holy spirit. Is it ever so, that, when there cometh unto you a messenger (from Allah) with that which ye yourselves desire not, ye grow arrogant, and some ye disbelieve and some ye slay? (Al Quran 2-90)

لَتَجِدَنَّ أَشَدَّ النَّاسِ عَدَاوَةً لِّلَّذِينَ آمَنُواْ الْيَهُودَ وَالَّذِينَ أَشْرَكُواْ وَلَتَجِدَنَّ أَقْرَبَهُمْ مَّوَدَّةً لِّلَّذِينَ آمَنُواْ الَّذِينَ قَالُوَاْ إِنَّا نَصَارَى ذَلِكَ بِأَنَّ مِنْهُمْ قِسِّيسِينَ وَرُهْبَانًا وَأَنَّهُمْ لاَ يَسْتَكْبِرُونَ

Strongest among men in enmity to the believers will you find the Jews and Pagans; and nearest among them in love to the believers will you find those who say, “We are Christians”: because amongst these are men devoted to learning and men who have renounced the world, and they are not arrogant. (Al Quran 5-83)

الَّذِينَ يُجَادِلُونَ فِي آيَاتِ اللَّهِ بِغَيْرِ سُلْطَانٍ أَتَاهُمْ كَبُرَ مَقْتًا عِندَ اللَّهِ وَعِندَ الَّذِينَ آمَنُوا كَذَلِكَ يَطْبَعُ اللَّهُ عَلَى كُلِّ قَلْبِ مُتَكَبِّرٍ جَبَّارٍ

“(Such) as dispute about the Signs of Allah, without any authority that had reached them, grievous and odious (is such conduct) in the sight of Allah and of the Believers. Thus does Allah, seal up every heart – of arrogant and obstinate Transgressors.” (Al Quran 40-36)

In Tirmizi, there is a hadith that says a person who has an iota of arrogance will not enter paradise.

2: Fear of Loss

فَمَا آمَنَ لِ مُوسٰى إِلاَّ ذُرِّيَّةٌ مِّن قَوْمِهِ عَلَى خَوْفٍ مِّن فِرْعَوْنَ وَمَلَئِهِمْ أَن يَفْتِنَهُمْ وَإِنَّ فِرْعَوْنَ لَعَالٍ فِي الأَرْضِ وَإِنَّهُ لَمِنَ الْمُسْرِفِينَ

But none believed in Moses except some children of his people, because of the fear of Pharaoh and his chiefs, lest they should persecute them; and certainly Pharaoh was mighty on the earth and one who transgressed all bounds. (Al Quran 10-83)

3: Love for traditions and forefathers

وَإِذَا قِيلَ لَهُمْ تَعَالَوْاْ إِلَى مَا أَنزَلَ اللّهُ وَإِلَى الرَّسُولِ قَالُواْ حَسْبُنَا مَا وَجَدْنَا عَلَيْهِ آبَاءنَا أَوَلَوْ كَانَ آبَاؤُهُمْ لاَ يَعْلَمُونَ شَيْئًا وَلاَ يَهْتَدُونَ

When it is said to them, :Come to what Allah has sent down, and to the Messenger; they say, :Sufficient for us is that on which we have found our forefathers. Is it so, even though their forefathers knew nothing, and had no guidance either? (Al Quran 5:105)

4: Jealousy

إِنَّ الدِّينَ عِندَ اللّهِ الإِسْلاَمُ وَمَا اخْتَلَفَ الَّذِينَ أُوْتُواْ الْكِتَابَ إِلاَّ مِن بَعْدِ مَا جَاءهُمُ الْعِلْمُ بَغْيًا بَيْنَهُمْ وَمَن يَكْفُرْ بِآيَاتِ اللّهِ فَإِنَّ اللّهِ سَرِيعُ الْحِسَابِ

Truly, the (recognized) religion in the sight of Allah is Islam . Those who have been given the Book did not differ (among themselves) until after the knowledge had come to them, (and all this) due to envy against each other. Whoever denies the verses of Allah, then, Allah is swift at reckoning. (Al Quran 3-20)

So the question is, how to we know whether we have above inhibitors, and if we do, how do we get rid of them?