Let's look at your or a donor's resources that are given when you do good. It could cost you time or effort, either if you've got to volunteer, or you work at a local food bank, or even actively listen or even stop to smile and say hello to someone. The other costs of donations that could be in-kind when you donate, maybe your old clothes or [inaudible] or straight-up cash and that could be small, like $0.50 you may put in a jar that's raising money to save the kids or UNICEF for our boxes or hundreds of thousands of dollars that you could donate to charitable course. If you're thinking of the things that you can do with your time and think of the things you can do with your money, how do we choose between time and money when you want to be generous? Should you give your time? Should you give your money? Should you give both? How does one make a choice? How do you, as a donor, make a choice? When was the last time you were generous? Was it with your time? Was with your money? There's always a trade-off to be made. For example, if you give up an extra hour of work to go and volunteer, then you're really giving up the money associated with that hour of labor, for example, or you could be giving up some of your leisure time, or you could just forfeit an hour of sleep and go to wake up early because you've promised to take some care or somebody's children or somebody's dog. Anyway, we're all faced with constraints. Whether we're giving money or whether we are giving time, we're faced with constraints. If you're giving goods and services, goods either cost you money and money constraint is your budget constraint. How much money you have, how much wealth you have, how many assets you have, all of that figures into your financial endowment. Similarly, you have a time constraint and the time constraint is a great equalizer. Trust me, Warren Buffett and I have the different budget constraints but we have the same time constraints. We are all exposed to 24 hours a day. There are difference in money constraints amongst people, between people, but time constraints are pretty well similar. Give or take, maybe some people need more sleep than other people, some people need more time to get ready in the morning than other people but by large, we have 24 hours a day and that's a great equalizer. How did these constraints change over a lifetime? Clearly, my time constraints over my lifetime, every single day we're not the same. Usually, when you're in preschool or grade school, you seem to have a lot more discretionary time. As you get into middle school and high school, suddenly you realize, "Oh my gosh, I've got to do my homework. I've got to make sure my grades are good, I have to get into college, " so your discretionary time goes down. Then you get into college and people have adapted to doing homework and working hard, but they've also found that they've managed their time better so they might peak on the discretionary time. Then when I got into my 30s and 40s and I had kids, my discretionary time went away completely. Some of you who have kids might realize that, that just the 20 minutes you have a shower and get ready in the morning you're almost happy. That's your discretionary time. But really your discretionary time goes down. Then when you get into your 50s and get older, your discretionary time goes up because your kids are away, you may have retired from work, and for all kinds of reasons, you suddenly find yourself with lots of time. Clearly, your time constraints have changed. Your income constraint is generally a very tight. When you're preschool, in grade school, and middle school, most of us don't even have an allowance. It's not saying that you don't have any discretionary, all I'm saying is your discretionary income is very low, and as you get older, your discretionary income goes higher. Clearly, it goes higher as you get in your 50s because you have obligations of putting your children through university, through school, plus your income is rising, you're getting your promotions, you're getting better at work, for whatever reason you might have saved, you've invested, your discretionary income gets higher. As you get older and 50s and into retirement, people's incomes go high. This is on average when we look at time and money constraint. If these constraints are changing over our lifetime, then your trade-offs, should I volunteer or should I give my money will also change. I'm not saying that these money and constraints are fixed. My second question is, can we change our money constraint? How can we change our budget? Is our budget fixed or can we change it? Well, the answer might be obvious, we'll just work longer hours. If you work longer hours, and especially if you're narrowly paid worker, you can work overtime, work longer hours, or even if you're a salaried worker, you can take a second job. You can rely and make more money. Our money constraint is highly related to our time constraint, but we can expand on money constraint. Can we increase our time constraint? On a fundamental level, no, because it's 24 hours but you can expand your time constraint by buying time-saving devices. Another way to save time is you can outsource. You can increase both your time and money constraints, but not when the fundamental 24 hours, but what do you do in those 24 hours. You can gain back your discretionary time. When you're choosing to give money or time, so we're just going to look at those two things when you're trying to be generous, giving time or money, you will incur costs of that decision-making both in time and money there are constraints, even if you're a billionaire or even if you're somebody without work and have no commitments to working or childcare, you still have time constraints.