What can be said at all can be said clearly; and whereof one cannot speak thereof one must be silent

One often makes a remark and only later sees how true it is

Now speak, / Or be for ever silent.

Speak for yourself and from yourself, or be silent.

Don't get involved in partial problems, but always take flight to where there is a free view over the whole single great problem, even if this view is still not a clear one.

A philosophical problem has the form: I don't know my way about.