سهر العيون لغير وجهك ضائع * و بكاؤهن لغير فقدك باطل. - Al-Ghazali

An important part of our knowledge of God arises from the study and contemplation of our own bodies, which reveal to us the power, wisdom, and love of the Creator. His power, in that from a mere drop He has built up the wonderful frame of man; His wisdom is revealed in its intricacies and the mutual adaptability of its parts; and His love is shown by His not only supplying such organs as are absolutely necessary for existence, as the liver, the heart, and the brain, but those which are not absolutely necessary, as the hand, the foot, the tongue, and the eye. To these He has added, as ornaments, the blackness of the hair, the redness of lips, and the curve of the eyebrows.

Lintasan hati penggerak keinginan itu ada dua jenis; yang mengajak ke arah kejahatan atau yang membawa kepada akibat yang buruk, dan yang mengajak ke arah kebaikan atau yang mendatangkan manfa'at di akhirat kelak. Kedua-dua lintasan hati ini sangat berbeza di antara satu sama lain dan masing-masing mempunyai namanya yang tersendiri. Lintasan hati yang baik dinamakan ilham, dan lintasan hati yang dikeji dinamakan waswas.

Lintasan-lintasan hati ini adaah berupaya kejadian dan setiap kejadian itu tentu ada yang menjadi dan menyebabkannya. Kejadian-kejadian yang berlainan menunjukkan sebab-sebab yang berlainan pula. Terangnya sesebuah rumah itu tentulah bukan berpunca dari sesuatu yang menyebabkannya menjadi gelap. Begitu juga dengan keadaan terang dan gelapnya hati yang mana sebab kedua-duanya adalah berbeza. Sebab lintasan yang mengajak ke arah keyakinan dinamakan malaikat, dan sebab lintasan hati yang mengajak ke arah kejahatan dinamakan syaitan. Keadaan yang dengannya hati bersedia untuk menerima ilham kebaikan dinamakan taufiq, dan keadaan yang dengannya hati bersedia untuk menerima waswas (bisikan) syaitan dinamakan khazlan (pengecewa).

We attest that He is the Willer of all things that are, the ruler of all originated phenomena; there does not come into the visible or invisible world anything meager or plenteous, small or great, good or evil, or any advantage or disadvantage, belief or unbelief, knowledge or ignorance, success or failure, increase or decrease, obedience or disobedience, except by His will. What He wills is, and what He does not, will not; there is not a glance of the eye, nor a stray thought of the heart that is not subject to His will. He is the Creator, the Restorer, the Doer of whatsoever He wills. There is none that rescinds His command, none that supplements His decrees, none that dissuades a servant from disobeying Him, except by His help and mercy, and none has power to obey Him except by His will.