God did not address the call to Isaiah; Isaiah overheard God saying, "Who will go for us?" The call of God is not for the special few, it is for everyone. Whether or not I hear God’s call depends upon the state of my ears; and what I hear depends upon my disposition. "Many are called but few are chosen," that is, few prove themselves the chosen ones. The chosen ones are those who have come into a relationship with God through Jesus Christ whereby their disposition has been altered and their ears unstopped, and they hear the still small voice questioning all the time, "Who will go for us?" It is not a question of God singling out a man and saying, "Now, you go." God did not lay a strong compulsion on Isaiah; Isaiah was in the presence of God and he overheard the call, and realized that there was nothing else for him but to say, in conscious freedom, "Here am I, send me." Get out of your mind the idea of expecting God to come with compulsions and pleadings. When our Lord called His disciples there was no irresistible compulsion from outside. The quiet passionate insistence of His "Follow Me" was spoken to men with every power wide awake. If we let the Spirit of God bring us face to face with God, we too shall hear something akin to what Isaiah heard, the still small voice of God; and in perfect freedom will say, "Here am I; send me."
Wisdom From Oswald Chambers
When we no longer seek God for His blessings, we have time to seek Him for Himself. The Moral Foundations of Life, 728 L