Every one knows what it is to be _certain_ in regard to many things, just because, constituted as he is, he cannot doubt or disbelieve them.

He is _certain_ of his own existence, of the existence of other men, of the facts of his familiar consciousness, of many events long since past which are still clearly remembered, of certain abstract truths which are intuitively discerned or logically demonstrated.

These various objects of his thought may differ in other respects, and may occasion a corresponding difference in the _kind_ of Certitude which is conceived to belong to them; but they all possess the same generic character, and admit, therefore, of being classified under the same comprehensive category, as objects of our _certain_ knowledge.
In the current use both of philosophical and popular language, Certitude is spoken of in a twofold sense.

We speak of a belief or conviction of our own minds as possessing the character of Certitude, when it is so strong, and so firmly rooted that it excludes all doubt or hesitation;--we speak also of an object or event as possessing the same character, when it is so presented to our minds as to produce the full assurance of its reality.

Hence the distinction between _subjective_ and _objective_ Certitude.