A fountain will be opened to the house of David and the inhabitants of Jerusalem, to cleanse them from sin and impurity.@Zechariah 13:1
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William Cowper (1731-1800)

William Cowper, in Conyer’s Collection of Psalms and Hymns, 1772.

Cleansing Fountain 19th Century American camp meeting tune (🔊 pdf nwc).

This is one of the first hymns Cowper wrote after his first attack of temporary madness. Cowper had been promised a post as Clerk of the Journal to the House of Lords, but was dismayed upon learning he would have to undergo a public examination in the House before beginning his duties. This article from the North American Review, January, 1834, describes his dilemma, and how God prevented him from destroying himself:

As the time drew nigh, his agony became more and more intense; he hoped and believed that madness would come to relieve him; he attempted also to make up his mind to commit suicide, though his conscience bore stern testimony against it; he could not by any argument persuade himself that it was right, but this desperation prevailed, and he procured from an apothecary the means of self-destruction. On the day before his public appearance was to be made, he happened to notice a letter in the newspaper, which to his disordered mind seemed like a malignant libel on himself. He immediately threw down the paper and rushed into the fields, determined to die in a ditch, but the thought struck him that he might escape from the country. With the same violence he proceeded to make hasty preparations for his flight; but while he was engaged in packing his portmanteau his mind changed, and he threw himself into a coach, ordering the man to drive to the Tower wharf, intending to throw himself into the river, and not reflecting that it would be impossible to accomplish his purpose in that public spot. On approaching the water, he found a porter seated upon some goods: he then returned to the coach and was conveyed to his lodgings at the Temple. On the way he attempted to drink the laudanum, but as often as he raised it, a convulsive agitation of his frame prevented it from reaching his lips; and thus, regretting the loss of the opportunity, but unable to avail himself of it, he arrived, half dead with anguish, at his apartment. He then shut the doors and threw himself upon the bed with the laudanum near him, trying to lash himself up to the deed; but a voice within seemed constantly to forbid it, and as often as he extended his hand to the poison, his fingers were contracted and held back by spasms.

At this time one of the inmates of the place came in, but he concealed his agitation, and as soon as he was left alone, a change came over him, and so detestable did the deed appear, that he threw away the laudanum and dashed the vial to pieces. The rest of the day was spent in heavy insensibility, and at night he slept as usual; but on waking at three in the morning, he took his penknife and lay with his weight upon it, the point toward his heart. It was broken and would not penetrate. At day break he arose, and passing a strong garter around his neck, fastened it to the frame of his bed: this gave way with his weight, but on securing it to the door, he was more successful, and remained suspended till he had lost all consciousness of existence. After a time the garter broke and he fell to the floor, so that his life was saved; but the conflict had been greater than his reason could endure. He felt for himself a contempt not to be expressed or imagined; whenever he went into the street, it seemed as if every eye flashed upon him with indignation and scorn; he felt as if he had offended God so deeply that his guilt could never be forgiven, and his whole heart was filled with tumultuous pangs of despair. Madness was not far off, or rather madness was already come.

After recovering, Cowper came to realize how God can erase the stain of any sin.

There is a fountain filled with blood
Drawn from Emmanuel’s veins;
And sinners plunged beneath that flood
Lose all their guilty stains.
Lose all their guilty stains,
Lose all their guilty stains;
And sinners plunged beneath that flood
Lose all their guilty stains.

The dying thief rejoiced to see
That fountain in his day;
And there have I, though vile as he,
Washed all my sins away.
Washed all my sins away,
Washed all my sins away;
And there have I, though vile as he,
Washed all my sins away.

Dear dying Lamb, Thy precious blood
Shall never lose its power
Till all the ransomed church of God
Be saved, to sin no more.
Be saved, to sin no more,
Be saved, to sin no more;
Till all the ransomed church of God
Be saved, to sin no more.

E’er since, by faith, I saw the stream
Thy flowing wounds supply,
Redeeming love has been my theme,
And shall be till I die.
And shall be till I die,
And shall be till I die;
Redeeming love has been my theme,
And shall be till I die.

Then in a nobler, sweeter song,
I’ll sing Thy power to save,
When this poor lisping, stammering tongue
Lies silent in the grave.
Lies silent in the grave,
Lies silent in the grave;
When this poor lisping, stammering tongue
Lies silent in the grave.

Lord, I believe Thou hast prepared,
Unworthy though I be,
For me a blood bought free reward,
A golden harp for me!
A golden harp for me,
A golden harp for me;
For me a blood bought free reward,
A golden harp for me!

’Tis strung and tuned for endless years,
And formed by power divine,
To sound in God the Father’s ears
No other name but Thine;
No other name but Thine,
No other name but Thine;
To sound in God the Father’s ears
No other name but Thine.