Value equals price over time. Price is the cost in terms of money and energy required to obtain a particular item or experience. Time in this instance is the amount and quality of use or benefit obtained from a particular expenditure.
Material objects have a definitive value in terms of price and energy, with exceptions made for sentimental value. They cost a certain amount to acquire and maintain and have a fairly definitive lifespan of usefulness.
Experiences, such as education and travel, have an indefinite and fluctuating value, which often appreciates over time, in terms of social benefit, enhanced understanding, and memory.
These two Rules of Value suggest investing in one category more heavily than the other.