I was led to serious study of the causes and effects of happiness and unhappiness by observations of the pitiable neglect of the science of menticulture, (which is the science of fundamental means), and the science of happiness (which is the science of ultimate desirable ends), in materially civilized communities, and by persons who have mastered, and are already possessed of, the physical means to comfort and happiness. This neglect is not surprising when we reflect that all available time and all available thought have been excitedly employed in developing material, physical _means_, to the exclusion of the thought of cultivating the end; to the harnessing and training of the forces of Nature, to the exclusion of planning for their best uses; but it will be surprising if, however, in the near future, the ends are not scientifically cultivated, now that the fundamental as well as the physical means are understood, and the leisure to apply them is secured. More than forty years of observation, and upwards of three years of study, analysis and arrangement with a fixed purpose, have enabled me to suggest changes of attitude towards the problems of life that have not failed to bring more or less strength and happiness to all who have adopted them, as attested by thousands of written and verbal communications and by report. This is literally true, and the statement of it is warranted by the merit of the results, removed from any personality in connection with it. The underlying cause of all weakness and unhappiness in Man, heredity and environment to the contrary notwithstanding, has always been, and is still, _weak habit-of-thought_. This is proven by the observed instances in which _strong habit-of-thought_ has invariably made its masters superior to heredity, and to environment, and to illness, and to weakness of all kinds, and has redeemed them from non-success and misery, to the enjoyment of success, honor and happiness. It has also been proven that none are so ill-favored as to be exempt from regeneration by the influence of optimistic thinking, and none so plain, nor even so ugly, as judged by the world's standards of beauty, but that the radiance of pure thought will make them more beautiful than their brothers of nobler mien and more symmetrical physique, but whose thoughts are poisoned by fear and by selfishness. Happiness is not dependent upon wealth, and wealth does not necessarily bring happiness, but both are dependent upon _good-habit-of-thought_; for _good-habit-of-thought_ develops _appreciation_, which is the measure of all wealth, and _appreciation_ leads to the _habit-of-feeling_ and the _habit-of-action_ which produce happiness.