There are two types of seniors mentioned in the verse: the white-haired and the old one. Likewise, there are two actions mentioned in the verse: to rise up, and to honor or glorify. Rising, or standing up, is mandated for the white-haired, and glorifying is mandated for the old one. Who are we talking about, and what are these behaviors teaching us?
The commentaries explain that the white-haired one is simply an aged person, regardless of their knowledge or character. If they have reached old age, we are to rise up before them. The old one, in Hebrew "zaken," refers to one who has "acquired wisdom." Because they are not just elderly, but also wise and righteous, a higher level of honor must be accorded, we must "glorify the countenance of the old one."
The sages read the verse in a way that implies that both the white-haired and the sage deserve both forms of respect, rising up and being glorified. If so, we need to understand why the elderly one, who is not a scholar or an exceptionally righteous one, receives the same treatment as the older sage. And more, the verse could've been rewritten simply, as follows: "You shall rise up and glorify the white-haired one and the elderly sage."
A possible reason they are both worthy of standing and glorifying is that they both teach us important life lessons. The Torah never tells us to bow to them, because that action is exclusively for the benefit of these elderly people. The Torah wants us to honor them not just for them, but for ourselves as well. It is obvious what we can learn from the elderly sage, as they have much wisdom to impart. But what about the white-haired non-sage?
First of all, any human being who reaches an elderly age, has amassed a wealth of life experience. For sure, elderly people can hold wrong opinions, and can even be of evil character. But generally, their life wisdom is something that younger people need to access.
Some commentaries bring a negative reason to honor them, in that we learn from imperfect older people in an inverse way. We learn from them how not to be. Hugh Hefner, as an extreme example, is a tragic elderly figure. His entire life was given over to lust. Well into his 80s, he felt forced to keep up that illusion, hosting parties at his mansion as if he were 30 years old, although now he was fueled by Viagra. How tragic! Do we really need to honor him?
Certainly not, but we do need to learn from him. We need to learn the lesson that a life wasted on lust and passion brings no fulfillment. When the contrast his example with that of an elderly Torah scholar, our own correct path in life becomes clearer. We have a choice to make.
I believe that is the deep meaning of this verse, and why it was written in two parts. If we rise up for the imperfect elderly one, and learn from their example even in a negative way, we will come to glorify the countenance of the elderly sage. That negative learning may be the most valuable lesson of life! Our sages teach us in the Mishna, "whoever learns even one thing from his friend must show him respect." Learning by seeing the negative consequences of poor life choices is learning, and even though the subject is not an exceptionally worthy one, they have done us a great service. We honor them because of the lesson they are teaching us, even if it is not intentional.
But in most cases, they can teach us an intentional lesson. In most cases, a simple elderly person may have a powerful spiritual message to impart. I recall reading of a pastor who had been kidnapped and nearly killed as a child by a sexual predator. Years later, after he grew up, he became aware that this criminal, who had never been convicted, was living in an old age home. He mustered his strength, and went to meet the man who had left him for dead when he was just a young boy.
At first, the man denied that he had anything to do with the event, and claimed not to know who this pastor was. The pastor, who had every moment of that encounter of his youth engraved in his memory, told him the story step by step. Finally, the old man broke down in tears, and began begging for forgiveness. And that is the most powerful lesson of old age, the lesson of repentance.
For this, we have our patriarch Abraham to thank. According to the sages, Abraham was the first human being to grow old. The reason given was that until he introduced old age, people couldn't tell the fathers from the sons apart. An explanation that I heard relates directly to the issue of repentance. Why do old people repent, and gained such wisdom? Because of two things: 1. They become more aware of their legacy, and 2. Their passions and drives become weaker, allowing their spirituality to become strong.
Aging is the gift of Abraham. And, so, many rabbis interpret this verse to refer to Abraham himself. They focus on the phrase "to rise up," and interpreted to mean "repent." Thus, the verse becomes a blueprint for life: Repent before you become white-haired, and as a result you will have a glorified old age.
I wish to add that "rising up" is an important instruction to us. When a person is sitting, they are not accomplishing or changing. When they stand up, they are now ready to move, change things in the world and accomplish. Rise up before it's too late, and learn from the example of the glorious old one, Abraham. Abraham never tired of spreading God's name in the world. When he was in pain after his circumcision, he forced himself to run out to the road to welcome in guests. When guests came to Abraham's tent, he taught them to give thanks to God for the food they eat and the blessings they have. Abraham traveled the land in every direction, calling out in the name of the Lord.
If was this Abraham who consciously chose to age, so that his lessons would continue to posterity. They must inspire us to rise up, throw off the laziness that paralyzes us, and begin following his example of spreading God's name and filling the world with loving kindness.