What is the most important thing lost in time?

From generation to generation what knowledge or (insert x here) is the worst thing to lose? Meaning and understanding are lost over time from generation to generation, but what specifically is the worst to lose?
Answers

Foofa

The loss that's coming into clear focus in my country, the US, is the decision to stop teaching any kind of substantive government or civics classes for the past few decades. We now have grown adults with college degrees who just found out in 2016 that the Electoral College is a thing. We have educated journalists positing all sorts of things that are clearly unconstitutional. It seems like nobody knows anything about how things work around here anymore (not leastly the current President who is as light on social studies knowledge as the rest).

thegreatone

Life is the most important thing lost in time.

Knightingale

Survival skills. If something were to happen like another depression, modesty wouldn’t keep you from starvation. Planting, harvesting, recognition of edible and poisonous plants, hunting and trapping prey, making a shelter and starting a fire.. Filtering water or if there is no water readily available what plants can keep you hydrated. Medicinal plants..

Johnny

The records of our history..

Elevo

The sense of modesty is the most important and would devastate the world if it were lost. Slowly, we are losing it. Go back in time, around 50 years or less, it was very extreme to see even half naked ladies on magazines, which was when Playboy was introduced. Now, it's becoming a trend to talk about sex and such explicit things in their songs. Yes, there is music and art that is very important when it has these things but it's being thrown around like it's nothing nowadays. Most rap these days have no talent, no underlying meaning, it's just a way to milk the money from the suckers. The children of this generation are losing modesty and self discipline. Society has become soft and people are now throwing fits when they're not given what they want because they're exposed to things that shouldn't be seen yet. We are speeding up the growing process and losing respect for ourselves and society. That's my opinion anyways.