We'll not know enough to know which stocks to buy.

They won't know enough to know when to buy them.

But they don't have to...

...because they can buy all of America through an index fund.

And then they just have to be sure they don't jump in at exactly the wrong time.

And they won't know what's exactly the wrong time...

...so therefore, they should put their money in over a period of time.

And they'll have some periods that are wonderful and some that weren't so good...

...but overall, they will do fine over time.