True faith I may call the grand tidal wave of the soul. I will endeavour to explain the expression. We see the river Thames day by day ebbing and flowing. What causes this change? You answer, "It is produced by the sea in the Channel alternately coming up and retiring." It is a true explanation. But what makes the sea of the Channel alternately come up and retire? There is what is called "a grand tidal wave" that comes across the Atlantic Ocean, which, as it ebbs and flows, affects all the minor tides of the neighbouring seas; and thus the tide of the Channel, and that of the river Thames, ebb and flow in unison with this huge Atlantic wave.
In the same way faith is the tidal wave of the soul; and all the graces and fruits of the Spirit ebb and flow just as faith rises, or just as faith sinks. If faith rises in the soul, all the graces and fruits of the Spirit rise with it; light increases, life is deepened, the fear of God strengthened, hope brightened, and love augmented. And when this great tidal wave of faith falls in the soul, all the minor tides of the Spirit's graces fall in unison with it.
Thus when faith recedes and becomes low in the soul, all the other graces of the Spirit sink with it; consolation ebbs out altogether, hope recedes to a narrow streamlet, life dwindles to a scanty current, and love is reduced to a shallow channel. And as in the Thames we see, at low tide, the muddy banks which the stream has forsaken, so as faith sinks to a low ebb in the soul, there seems little else left but the mud and mire of corruption.
But what makes the grand tidal wave itself move? There is a cause for that also. It is drawn up by, and obeys the attraction of the sun. And is not this true spiritually of the grand tidal wave of faith in the soul? Is it not drawn up by the Sun of righteousness, as the natural sun draws up the wave of the ocean, and makes it ebb and flow? And when that glorious Sun ceases to draw up faith, does it not ebb and sensibly sink in the soul, as the natural sea sinks when the sun recedes from it?