Chapter Two of Kena Upanishad:

yadi manyase suvedeti dabhram evapi nunam tvam vettha brahmano rupam/ yadasya
tvam yadasya ca vedesu atha nu mimamsyam eva te manye viditam ||1||

If you believe that you know the form of Brahma then you know very little about his form. You know the form of that Brahma or you believe on the form represented by lords and other scholars, it is not clear, it is not sure.

naham manye suvedeti no na vedeti veda ca
yo nas tad veda tad veda no na vedeti veda ca ||2||

I do not know whether I know him correctly or not, neither I can say this that I do not know because I know something. The person who believes that he knows Brahma, he knows only that much or very little, he might know or not know as well.

yasyamatam tasya matam matam yasya na veda sah
avijnatam vijananatam vijnatam avijanatam ||3||

The person who believes that he does not know him, has understood him. The person who thinks that he has understood him does not know him. He is unknown for those who know him and known for those who do not know him. Because only this can be understood with respect to him.

pratibodha-viditam matam amrtatvam hi vindate
atmana vindate viryam vidyaya vindate amrtam ||4||

When a person understands him with knowledge then he can be known. When the sensory organs move towards the subjects then we understand, when they move towards the inner self the knowledge attained at that time is obstruction. A man becomes immortal with this knowledge. This conditions arises when the person is strong a weak person can never get this knowledge. The person getting in the trap of sensory organs becomes weak and gets into the related subjects. The only method to come out of this vicious cycle is to becomes strong, and adopt the path of knowledge. One needs to arouse his inner soul for this purpose. A person cannot become strong by tying himself to the worldly bonds. The strength is obtained from the soul, when you move away from the sensory organs and go back to the soul you attain strength. This is the condition of knowledge. Moving towards the subjects is understanding, and moving towards the soul is knowledge. Understanding is ignorance, knowledge is real education, practical knowledge. This knowledge is like nectar.

iha ced avedid atha satyam asti na ced ihavedin mahati vinastih
bhutesu bhutesu vicitya dhirah pretyasmal lokad amrta bhavanti ||5||

If you understand him in this world in this birth then it is fine, if you do not understand him, then it is destruction everywhere, the scholars and great human beings have found him in every particle, living – non-living and reached to the conclusion that He is the main basis for everything. Such people obtain nectar after death, they become immortal.

In the first part it has been said the life cycle does not proceed on its own there is a strong force driving it. The eyes cannot see that strength, the eyes see with it. It has no speech, the speech can only describe it. In this part it has been said that what is that part, how can we know it? The sages say that, that strength can be experienced in every particle on the earth, every body can feel it, the huge world is enough to experience its omnipresence, but one should understand that thinking that we have understood Him is illusion. What we see in this world and experience His presence is a common thing, this is understanding, we need knowledge to understand his real form, knowledge that is getting relieved from sensory organs and moving towards the inner soul, this condition gives this experience.