(This is) a Book, the Verses whereof are perfected (in every sphere of knowledge, etc.)
Allaah (The Most High) said:
الٓرۚ كِتَـٰبٌ أُحۡكِمَتۡ ءَايَـٰتُهُ ۥ ثُمَّ فُصِّلَتۡ مِن لَّدُنۡ حَكِيمٍ خَبِيرٍ
Alif-Lam-Ra. (This is) a Book, the Verses whereof are perfected (in every sphere of knowledge, etc.), and then explained in detail from One (Allah), Who is All-Wise and Well-Acquainted (with all things). 
Allaah (The Most High) said: This is a great Book and a noble revelation. [أُحۡكِمَتۡ ءَايَـٰتُهُ– the Verses whereof are perfected]; meaning: (Absolutely) perfect and excellent. Its information is (absolutely) truthful and its commandments and prohibitions are (absolutely) just. Its wordings are (absolutely) eloquent and its meanings are (absolutely) magnificent. [ثُمَّ فُصِّلَتۡ– And then explained in detail]; meaning: Distinguished (i.e. for its absolute excellence, truthfulness, perfection, infallibility etc) and explained with the loftiest of explanations. [مِن لَّدُنۡ حَكِيمٍ خَبِير— From One (Allah), Who is All-Wise and Well-Acquainted (with all things)]. He (Allaah) imposes all things (or all affairs) in their rightful places and positions them in their rightful positions. He neither commands nor prohibits except in accordance with His (absolute perfect) Wisdom. [خَبِير]- ‘Well-Acquainted’ with all apparent and hidden things.
And when it is the case that it’s (i.e. the verses of the Qur’aan) perfection and detailed explanation is from Allaah, The All-Wise and Well Acquainted (with all hidden and apparent things), then no question should be asked about its greatness and loftiness, and about it being gathered upon perfect wisdom and vast mercy.
 Noble Qur’aan Shaikh Taqiyudeen Al-Hilaali and Dr Muhsin Khan
 [Slightly paraphrased…see: Tayseer Al-Kareem ar-Rahmaan Fee Tafseer kalaam Al-Mannaan’ of Imaam Sadi