सत्यमेव जयते नानृतं सत्येन पन्था विततो देवयानः । येनाक्रमन्त्यृषयो ह्याप्तकामा यत्र तत् सत्यस्य परमं निधानम् ॥ (Mundaka Upanishad 3.1.6)
Truth (सत्) alone will be victorious, not the falsehood. By truth, the great path is widened/revealed, using that, seekers, who have given up all the desires, reach the ultimate destination. 

While we know truth alone wins, but, ‘what is that real truth?’. 

Many people say, what we ‘see’ is ‘the truth’. But, many of the things we saw earlier aren’t there anymore, and what we see today, will not be there in the future too, right. So, how can such things we see be ‘the truth’? 

For example, if we see our own photo, when we were, say 1 year old, and compare it with how we look today, there is a lot of differences, correct.. Then, which one is real us? 

Both right… Or Is it really? 

If we just increase the timescale and see the future 100 years later, there is no way we will be existing. So, the truth of our existence today is conditional on time, right… It is not an absolute truth. 

Also, If we further increase the timescale, say a few tens of billion years later, our Solar System or even our Galaxy is not going to survive in today’s form. 

That means, everything that we see today is just ‘conditional’ truth, i.e. truth which depends on time, not the real truth. 

Then what is the real truth, which doesn’t depend on time? For something to be independent of time, it needs to be there before the universe was formed (i.e. before Big Bang), and will need to be there even after the Universe is gone too (i.e. after Big Crunch). 

That alone is the REAL TRUTH, called ‘Brahman’ in Vedanta. 

And to top it all off, that ‘real truth’ is not somewhere far-far away in-universe, but rather very near, right inside us, we just need to give up limiting ourselves with the body, and desires. If we do that, as the shloka says, we will hit a wide great path, which will lead us to that real absolute truth. 

All the Best!