The subject of the Treatise is human nature, and its author, in the first book, On the Understanding, compares the human mind to a fragile and cracked vessel that must be cast 'into the open sea of human nature' in order to 'make a round of the world.'

Being aware of his own weaknesses, Hume finds that the philosophical critique he exerts on his mental capabilities leads him to confusion. Despite his human curiosity about the causal connections between things and his love for strict reasoning, his philosophical theory helps him recognize that the things we perceive as causes are products of the imagination.

When the senses, memory, and understanding are founded on the 'unstable and precarious' capacity of 'fictitious imagination,' we are led to conflicting beliefs. Therefore, philosophical reflection leads us to a dangerous dilemma: Can we rely on the 'trite suggestions of fictitious imagination,' which produce 'errors, absurdities, and ambiguities,' or must we rely on the 'general and more firmly established qualities' of the mind, namely reason and logic?

However, the latter approach undermines even the beliefs upon which our very survival depends: 'reason, when acting alone and according to the most general principles, undermines itself and cannot substantiate any belief, whether philosophical or of everyday life.'

The solution will come from human nature, which dispels philosophical melancholy but does not allow for the devaluation of philosophical thought: If superstition is to be countered and understanding of the world improved, then philosophizing is as natural as it is necessary.

Indeed, we should not merely yield to philosophical reflection, but cultivate a passion for philosophy, for 'the true skeptic must be hesitant both with his philosophical doubts and with his philosophical certainties.'

Thus 'we can hope for the establishment of a system or a set of views which, if they are not true, because such hope may be excessive, at least could withstand the scrutiny of the most critical examination.'

The present translation of the first book of the Treatise of Human Nature is the first in the Greek language.