Lord Siva and Lord Brahma are two chiefs of the demigods. They are full of mystic powers. For example, Lord Siva drank an ocean of poison of which one drop was sufficient to kill an ordinary living being. Similarly, Brahma could create many powerful demigods, including Lord Siva. So they are isvaras, or lords of the universe. But they are not the supreme powerful. The supreme powerful is Govinda, Lord Krsna. He is the Transcendence, and His transcendental attributes cannot be measured even by such powerful isvaras as Siva and Brahma. Therefore Lord Krsna is the exclusive shelter of the greatest of all living beings. Brahma is counted amongst the living beings, but he is the greatest of all of us. And why is the greatest of all the living beings so much attached to the transcendental topics of Lord Krsna? Because He is the reservoir of all enjoyment. Everyone wants to relish some kind of taste in everything, but one who is engaged in the transcendental loving service of the Lord can derive unlimited pleasure from such engagement. The Lord is unlimited, and His name, attributes, pastimes, entourage, variegatedness, etc. are unlimited, and those who relish them can do so unlimitedly and still not feel satiated. This fact is confirmed in the Padma Purana: