Freedom from the pair of opposites is a phrase that resonates specifically through Indian philosophy. The most common opposites that are mentioned are Pleasure-Pain, Comfort-Discomfort, Victory-Defeat, Honor-Disgrace, Attachment-Aversion etc. AND, yes, to those who would contend that happiness IS a goal for humans, and to be indifferent to Joy and Sorrow is ceasing to really live, the reply is that the goal is Bliss in the form of Nirvana. Sort of like, if you had to give up the pleasure of drinking today in order to become the CEO tomorrow, what would you choose? (YOU could choose to drink. The point, as I have mentioned before, is that Philosophers guide you to what THEY think is the desirable goal.)
Try to understand what Tiru says, given this context...
Atremendru allaR padubavo petraemendru ombudhal thaetraa dhavar - Tirukkural
Would he who clung not to his wealth grieve if he lost it? - Loose Translation
Yeah, yeah, I can hear that jeering laugh. If you fail to cling to your wealth, obviously you are going to lose it to some Nigerian millionaire or digital arrest or some such. (These days, nobody considers the possibility that you may lose it because of your generosity. If I suggested it, I'd end up becoming the subject matter of memes.) Then what would be the point in grieving it?
Tiru, though, has other meanings for that 'clung not to his wealth'. What he means is that you have not made your wealth your identity; not made it the core of your self-respect; not surrounded yourself with only those who respect you for your wealth. In other words, if you had considered your wealth as merely a possession and not the core of your personality OR your social position, you'd not grieve the loss of your wealth.
Think of, say, an author or a composer or a painter or a sculptor...their art is their identity, not their wealth. AND, if such a person, embraced the act of creation as his identity and not the successes that come out of it...would losing wealth cause him grief?
Think, then, of wealth as a metaphor for anything external that earns you social position. Your official position, your professional popularity, whatever. As long as you keep that at arms length from your own sense of identity; as long as you can understand the difference between people who like and respect YOU and those who respect your POSITION and treat the latter as unimportant...THEN you can retire without feeling a vacuum; lose that popularity and still be happy.
THAT, then, is what Tiru means. True happiness lies within. To cling to what you get from the world leaves you open to the grief that inevitably follows when the world denies it to you.