Whereas in the next world which is the realm of Power. God will execute His Will directly without the 'medium' of causes so that everything will happen instantaneously the Divine Name the All-Wise requires that in this world which is the realm of Wisdom. Divine Power should operate from behind the veil of causes and laws.
Because:
Opposites are mingled in this world where man is tested how he will use his free will and other faculties
1. Opposites are mingled in this world: truth with falsehood light with darkness good with evil white with black and so on. Since man in whose nature are ingrained inclinations towards both good and evil is tested in this world whether he will use his free will and other faculties in the way of truth and good or otherwise. Divine Wisdom has required that the veil of causes and laws should be drawn before the operations of Divine Power. If God had willed. He could be training the planets with His 'hands' in a way observable by us or He could have them administered by angels whom we could see openly and we would then not be speaking of the laws of causes involved such as gravitation. Or in order to communicate His Commandments. He could without sending any Prophets speak to each individual directly or in order to compel us to believe in His existence and Oneness. He could write His Name with stars on the face of skies. But in this case man's earthly existence could not be as it is an arena of trial. As a result of this trial good and evil have since the beginning of man's worldly existence been flowing through this world into the next one to fill its two mighty pools of Paradise and Hell.
God has made natural laws and causes a veil before His acts so that some unaware of the wisdom and good behind the things and events disagreeable to them should not criticize Him
2. Like the two sides of a mirror existence has two aspects or dimensions one visible and material the realm of opposites and (in most cases) imperfections and the spiritual realm which is transparent pure and perfect. There can be and actually are in the material dimension events and phenomena which appearing disagreeable to man. Those who are unable to perceive the Divine Wisdom behind all things may go so far as to criticize the Almighty for those disagreeable events and phenomena. In order to prevent that. God has made natural laws and causes a veil before His acts. For example so that man should criticize neither God nor His angel of death for the loss of his beloved ones or for his own death. God has placed between Himself and the phenomenon of death (among other 'agents' or 'causes' ) diseases and natural disasters.
Again on account of the essential imperfection of this world of testing and trial man encounters and suffers from many deficiencies and shortcomings. In absolute terms every event and phenomenon is good and beautiful in itself or in its consequences. Whatever God does or decrees is good beautiful and just. Injustices ugliness and evils are only apparent or superficial and arise from the errors and abuses of humankind. For example a court may pass an unjust sentence on you; but you should know that Destiny permitted that judgment because of a crime of yours which has remained hidden. Whatever befalls a man is usually because of self-wronging an evil he himself has done. However those who lack the sound reasoning and judgment necessary to understand the Divine Wisdom behind events and phenomena may impute directly to God the apparent ugliness or evils the imperfections and shortcomings experienced in worldly life. Whereas God is absolutely free from any kind of defect or imperfection.
Therefore to prevent people from ascribing to God the ugliness and evils they encounter in life. His Glory and Grandeur have required that natural causes and laws should be a veil before His acts while belief in His Unity demands that those causes and laws should not be ascribed to any kind of creative power.
If God Almighty acted in the world directly without the 'medium' of causes and laws man would have been unable to develop scientific knowledge nor live even an instant of happy life free of fears and anxieties.3. If God Almighty acted in the world directly without the 'medium' of causes and laws man would have been unable to develop scientific knowledge nor live even an instant of happy life free of fears and anxieties. It is thanks to God's acting from behind natural causes and laws that man is able to observe and study patterns in phenomena. Otherwise each event would be a miracle. The regularity within the flux and mutability of events and phenomena makes them comprehensible to us therefore awakens the desire in us to wonder and reflect which is a principal factor in the establishment of sciences. For the same reason we are able to some degree to plan and arrange our affairs in advance; consider how life would be if we were completely uncertain whether the sun would rise tomorrow! If God manifested His Names and Attributes directly without the 'medium' of causes and laws human beings could not endure them.4. Whoever owns such attributes as beauty and perfection desires to know them and make them known. God owns absolute beauty and perfection and is independent of all things needing nothing. He owns also a holy transcendent love and therefore a sacred desire to manifest His Beauty and Perfection. If He manifested His Names and Attributes directly without the 'medium' of causes and laws human beings could not endure them. He manifests them from behind causes and laws and by degrees within the confines of time and space so that we can build a connection with them reflect on them and perceive them. The gradual manifestation of Divine Names and Attributes is also a reason for our curiosity and wonder about them.These four constitute only some of the reasons why God acts through the 'medium'of natural laws and causes.