Another class of people have also to be taken into account, those whose hearts have lagged behind their heads. With their reason they cannot but accept the ideas of natural science. The burden of proof is too much for them. But those ideas cannot satisfy the religious needs of their souls,--the perspective offered is too dreary. Is the human soul to rise on the wings of enthusiasm to the heights of beauty, truth, and goodness, only for each individual to be swept away in the end like a bubble blown by the material brain? This is a feeling which oppresses many minds like a nightmare. But scientific concepts oppress them also, coming as they do come with the mighty force of authority. As long as they can, these people remain blind to the discord in their souls. Indeed they console themselves by saying that full clearness in these matters is denied to the human soul. They think in accordance with natural science so long as the experience of their senses and the logic of their intellect demand it, but they keep to the religious sentiments in which they have been educated, and prefer to remain in darkness as to these matters,--a darkness which clouds their understanding. They have not the courage to battle through to the light. There can be no doubt whatever that the habit of thought derived from natural science is the greatest force in modern intellectual life, and it must not be passed by heedlessly by any one concerned with the spiritual interests of humanity. But it is none the less true that the way in which it sets about satisfying spiritual needs is superficial and shallow. If this were the right way, the outlook would indeed be dreary. Would it not be depressing to be obliged to agree with those who say: "Thought is a form of force. We walk by means of the same force by which we think. Man is an organism which transforms various forms of force into thought-force, an organism the activity of which we maintain by what we call 'food,' and with which we produce what we call 'thought.' What a marvellous chemical process it is which could change a certain quantity of food into the divine tragedy of Hamlet." This is quoted from a pamphlet of Robert G. Ingersoll, bearing the title, _Modern Twilight of the Gods_. It matters little if such thoughts find but scanty acceptance in the outside world. The point is that innumerable people find themselves compelled by the system of natural science to take up with regard to world-processes an attitude in conformity with the above, even when they think they are not doing so.