"The idea is, that no matter what language a people speaks, all can understand the language of the heavens. Their message can be read much more easily than if they uttered an audible sound; for all people on earth cannot understand the same articulate speech, but all who have reason can read the simple language of the works of God.
Addison expresses this thought in the following beautiful lines: -
"The spacious firmament on high,
With all the blue, ethereal sky,
And spangled heavens, a shining frame,
Their great Original proclaim;
The unwearied sun, from day to day
Does his Creator's power display,
And publishes to every land
The work of an Almighty hand.
"Soon as the evening shades prevail,
The moon takes up the wondrous tale;
And nightly, to the listening earth
Repeats the story of her birth;
While all the stars that round her burn,
And all the planets in their turn,
Confirm the tidings as they roll,
And spread the truth from pole to pole.
"What though in solemn silence, all
Move round the dark terrestrial ball?
What though no real voice nor sound
Amid their radiant orbs be found?
In reason's ear they all rejoice,
And utter forth a glorious voice,
For ever singing, as they shine,
'The hand that made us is Divine.'"
The Gospel is the power of God, and the power of God is manifest in the things that He has made; therefore the Psalmist is speaking of the Gospel, which the heavens teach.
The Apostle Paul in Romans 10.15-18 shows that this is so, "How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things! But they have not all obeyed the gospel. For Isaiah says, Lord, who has believed our report? So then faith comes by hearing, and hearing by the word of God. But I say, have they not heard? Yes verily, their sound went into all the earth, and their words unto the ends of the world."
The apostle is here speaking about the Gospel, which, he says, all have not obeyed. Then he declares that all have heard, and as proof that they have all heard he quotes from Psalm 19, "Their line is gone out through all the earth, and their words to the end of the world."
Their words concerning what? Why, concerning the Gospel, of course. Thus we have a plain statement that the heavens do preach the Gospel. There is no man so illiterate that he cannot read the Gospel; no man so deaf or so isolated that he cannot hear a gospel sermon."
E.J.Waggoner