What is a sound investment?
A sound investment is one where you have the opportunity to invest in a quantity company at a reasonable price. The quality of the company is important, but the price you pay is even more so. Therefore, a lower quality company can still be a sound investment provided the price paid is attractive enough.
It is crucial to understand that the price you pay will be the major determinant of your investment return. You can buy shares in the best company in the world but if you pay too high a price, the investment will not be a sound one.