Krishna mentioned that one realises Brahma when one strives for liberation by taking refuge in HIM (7.29) and Arjun enquires as to what is Brahma (8.1). Krishna says that Brahma is that which is the 𝙖𝙠𝙨𝙝𝙖𝙧𝙖𝙢 (imperishable or indestructible or permanent) and 𝙥𝙖𝙧𝙖𝙢𝙖𝙢 (supreme) (8.3). This implies that there is nothing beyond it and it's not dependent on any external factors. On the contrary, we only know about those things which are changing, impermanent and perishing.
Our own physical body constantly changes. It is estimated that 95 percent of it gets replaced in about 7 years without our knowledge while our DNA remains constant. The solar system would perish in 4 billion years and the universe in about 150 trillion years. Similarly, our thoughts keep changing. Opinions about things, people and situations vary with time; people form diametrically opposite opinions based on the same facts as we see things differently like how the five blind men perceive the elephant differently. Even our goals change, especially once we reach there.
Our senses are the biggest hurdle in the path of realising the state of Brahma. They are evolved to see the changes in the outside world in terms of sounds, light, smell and touch. Undoubtedly, this ability is essential for survival, but at the same time this prevents us from realising the '𝙖𝙠𝙨𝙝𝙖𝙧𝙖𝙢' as it is said that 'what brought us here (survival) won't us take there (Brahma)'. That's why Krishna cautions about senses on many occasions.
It's about shedding the impermanent by understanding impermanence; what remains finally is the '𝙖𝙠𝙨𝙝𝙖𝙧𝙖𝙢'. It's like realising a stable pivot in a swinging pendulum; the fixed axle of a rotating wheel. It's about not getting attached to impermanent ones (creation) and always keeping sight of the eternal (creativity) which is realising oneness in diversity.