For our contemporary readers this most often is addressed in the verb “observation” as to what may be observed in any one or all of the five senses that human beings are capable of. This becomes vitally important in logic because of three reasons:
1. When a proposition is being presented there needs to be a consistent mechanism from which to prove the given premise.
2. If I just say I feel that the sky is blue, this of course is subjective to me and it could only be subjective to me so that you would never be able to confirm the premise that the sky is blue.
3. Finally, without having a consistent understanding of perception and the objects and references associated with it, it would be impossible for human beings to communicate at all.
Let’s take the last point in relation to the english alphabet. If I cannot observer through the sense of my vision that the order of the alphabet follows: A, B, C, etc.., but you can how would I ever be able to form words that you would understand? So it is not just perception that needs consistency, but objective perception so ideas can be understood on common ground between persons.
Check back soon as I will cover the “Nature of Ideas” and how to obtain new ones.