Source: Light within me –by: Imam Khomeini (S.A) - p.134-135
Every possibly existing being is Allah's name, His deed and a manifestation of His glory. He Himself says: Allah is the Light of the heavens and the earth (Surah an-Nur, 24:35). Every possibly existing being is a manifestation of the glory of Allah, but not Allah. Everything that appears in the world is so related to the source of its origin that it cannot have any independent existence. That is why it has been said in the Qur'an that: 'Allah is the light of the heavens and the earth.'
If it is admitted that the definite article 'al' in al-Hamdu indicated 'Comprehensiveness', the verse would mean that every praise by whomsoever it might be expressed, takes place with the name of Allah.
As he who praises Allah, is himself, one of Allah's names, it may be said that in a sense the praiser and the praised are one and the same. One is the manifestation and the other is the manifester. Some sayings of the Holy Prophet, such as: 'You are as You have praised Yourself', and 'I seek refuge from You in You', point in this direction. As the relationship between the praiser and the praised is that of passing away of the former in the latter, the former cannot claim that it is he who praises. In fact it is the 'praised' who praises Himself, for the praiser has passed in Him.
According to another possibility it may be said that the definite article in 'al-hamdu' is not for showing comprehensiveness, but it indicates that the word, 'hamd' signifies general praise without any qualification being attached to it. In this case the praise of Allah performed by us is not actually His praise. His praise is only that which He performs Himself. The reason is that Allah is the Infinite Being while all others are finite. Any praise expressed by a finite being will naturally be finite and limited and therefore it cannot be the praise of the infinite Being.
While mentioning the first alternative we said that every praise was Allah's praise. Even when you think that you are commending the merits of a beautiful handwriting, you are actually extolling Allah. Similarly when you believe that you are paying tributes to the world, in that case also you are praising none but Allah. That is why, while describing the first alternative or the first possibility, we said that every praise was that of Allah, whosoever might be the praiser, for nothing except Allah has an independent existence. Every excellence, every beauty and every perfection belongs to Him only. If Allah withdraws the manifestation of His glory, nothing would be existing any longer.