And then there is the other side, which I only name, moral purity.  Light is the emblem of purity as well as the emblem of knowledge, and if we are Christians we have within us, by virtue of our possession of an indwelling Christ, a power which teaches and enables us to practise a morality high above the theories and doings of the world.  But upon this there is the less need to dwell, as it was involved in our consideration of the previous figure of the salt.

II.  And now the next point that I would make is this, following the words before us—­the certainty that if we are light we shall shine.

The nature and property of light is to radiate.  It cannot choose but shine; and in like manner the little village perched upon a hill there, glittering and twinkling in the sunlight, cannot choose but be seen.  So, says Christ, ’If you have Christian character in you, if you have Me in you, such is the nature of the Christian life that it will certainly manifest itself.’  Let us dwell upon that for a moment or two.  Take two thoughts:  All earnest Christian conviction will demand expression; and all deep experience of the purifying power of Christ upon character will show itself in conduct.

All earnest conviction will demand expression.  Everything that a man believes has a tendency to convert its believer into its apostle.  That is not so in regard to common every-day truths, nor in regard even to truths of science, but it is so in regard to all moral truth.  For example, if a man gets a vivid and intense conviction of the evils of intemperance and the blessings of abstinence, look what a fiery vehemence of propagandism is at once set to work.  And so all round the horizon of moral truth which is intended to affect conduct; it is of such a sort that a man cannot get it into brain and heart without causing him before long to say—­’This thing has mastered me, and turned me into its slave; and I must speak according to my convictions.’

That experience works most mightily in regard to Christian truth, as the highest.  What shall we say, then, of the condition of Christian men and women if they have not such an instinctive need of utterance?  Do you ever feel this in your heart:—­’Thy word shut up in my bones was like a fire.  I was weary of forbearing, and I could not stay’?  Professing Christians, do you know anything of the longing to speak your deepest convictions, the feeling that the fire within you is burning through all envelopings, and will be out?  What shall we say of the men that have it not?  God forbid I should say there is no fire, but I do say that if the fountain never rises into the sunlight above the dead level of the pool, there can be very little pressure at the main; that if a man has not the longing to speak his religious convictions, those convictions must be very hesitating and very feeble; that if you never felt ’I must say to somebody I have found the Messias,’ you have not found Him in any very deep sense, and that if the light that is in you can be buried under a bushel, it is not much of a light after all, and needs a great deal of feeding and trimming before it can be what it ought to be.