The message of this song is much clearer once we know of the story told by Dwight L. Moody, a revival preacher. (The story was the inspiration for the song.)
"On a dark stormy night...a boat, rocking and plunging, neared the Cleveland harbor. 'Are you sure this is Cleveland?' asked the captain, seeing only one light from the light-house. 'Quite sure,' replied the pilot. 'Where are the lower lights?' 'Gone out sir.' 'Can you make the harbor?' 'We must, or perish, sir!'
"With a strong hand and a brave heart the old pilot turned the wheel. But alas, in the darkness he missed the channel, and with a crash upon the rocks the boat was shivered, and many a life lost in the watery grave. Brethren, the Master will take care of the great light-house; let us keep the lower lights burning." (Quoted in Phil Kerr, Music in Evangelism p. 163)"
"The beam of light from the lighthouse, "our Father's mercy," never goes out. But some struggling people - metaphorically, the sailors lost on the dark sea - need more immediate aid than the distant beam of the lighthouse. Those who seek to carry out the will of the Father will keep the lower lights burning, so that anyone who wishes to find the safety of the harbor can turn at once in the right direction." (Karen Lynn Davidson)
Love this song. Press on the following link to enjoy a beautiful rendition.
"Brightly Beams Our Father's Mercy"