_In the sixth and last place,_ reason and conscience are insufficient to give us a full and complete system of morality, or moral truths. Let the system of morality taught and believed by the best and wisest of heathen nations, be candidly examined and critically inspected, and it will appear a maimed and imperfect, a broken and defective system. They had endless contentions about what they termed the CHIEF GOOD, that is, the real duty and happiness of man. One of their most eminent moralists reckons up more than one hundred different and contradictory opinions on this subject. Some placed it in self-indulgence: some in riches--some in insensibility--and all in that which never can render us blessed, and in which it can never be found.--Had any one leisure, and could summon up a sufficient stock of patience to collect from all the heathen writers on moral subjects, their various and self-contradictory rules of moral living, we should see how utterly unable _mere_ reason is to form a complete system of moral virtue. It would be great injustice to the subject before us, not to remark here, that some of the greatest moralists among the Greeks and Romans, had seen the writings of Moses, or the New-Testament, and had gleaned from them, a great proportion of the moral lessons which they delivered. Many of them, which is indeed much to their honour, travelled into the famous countries of Asia, where mankind were _first planted_ by the adorable Creator, and where communications from the Almighty were first made to man, and they returned home to their own countries, enriched with the learning of others. But with all these advantages none of them, Socrates, Plato, or Seneca, who were universally known to be most renowned for moral sayings, formed any thing like a full and perfect system. They leave out many important virtues. They admit many odious and horrible vices; such as self-murder, cruelty, incest, and revenge.--And they place all the virtues on a wrong foundation, and persuade to the practice of them from improper and weak, or sinister and wicked motives. Even the celebrated Cato, who gave forth many moral maxims--who was called honest, just, inflexible in integrity--who was said by his contemporaries to be possessed of a stern virtue, put an end to his own life, because he could not bear to be a witness of the corruption and degeneracy of the age, in which he lived.--Few crimes perpetrated by man can be more heinous than self-murder. There is something terrifying in the extreme to think of ushering ourselves, uncalled, unbidden into the presence of the Deity and into the invisible world. Many nations now in the world where the Gospel was never known or christian doctrines propagated, have no idea at all of the Creator of the universe, or immortality of the soul, or pious duties, or fear of, or love to God.--The heathen tribes of this Land, as those tell us who have had the best opportunities of information, where no