What is meant is, that the facts of the materialist are the only facts we can be certain of; and because these can give man no moral guidance, that therefore man can have no moral guidance at all.
Let us illustrate the case by some example that is mentally presentable.
Some ruined girl, we will say, oppressed with a sense of degradation, comes to Dr.Tyndall and lays her case before him.

'_I have heard you are a very wise man_,' she says to him, '_and that you have proved that the priest is all wrong, who prepared me a year ago for my confirmation.
Now tell me, I beseech you tell me, is mine really the desperate state I have been taught to think it is?
May my body be likened to the temple of the Holy Ghost defiled?
or do I owe it no more reverence than I owe the Alhambra Theatre?
Am I guilty, and must I seek repentance?
or am I not guilty, and may I go on just as I please ?' 'My dear girl_,' Dr.Tyndall replies to her, '_I must shake my head in doubt.

Come, let its lower our heads, and acknowledge our ignorance as to whether you are a wretched girl or no.

Materialism is confounded, and science rendered dumb by questions such as yours; they can, therefore, never be answered, and must always remain open.

I may add, however, that if you ask me personally whether I consider you to be degraded, I lean to the affirmative.