The greatest safeguard of purity with all that it means for the preservation of health and strength is the practice of self-denial with regard to the luxuries of life. No element in life has emphasized that and encouraged its practice so much or so constantly, and so persistently tried to train her children in it from youth as religion. It is almost impossible, for young people particularly, to keep right in this matter if they constantly indulge in luxuries. The very word luxury has come to be defined as "lust and lasciviousness and indulgence in lust", because there is such an almost inevitable connection between the exuberance of animal spirits which develops in connection with indulgence in luxuries of various kinds that the two words have almost necessarily come to have an intimate association. The word is applied to the friskiness or wantonness of animals, and it is very easy to understand its application. Men as well as animals who take more food than their occupations in life enable them to dispose of properly become similarly wanton or out of control. In Scriptural words they "wax fat and kick." Religion has encouraged innocent enjoyment of every worthy sort as a distraction of mind and an outlet for youthful energy, but has discouraged in every way possible that complete gratification of the senses or of bodily desires which is so likely to be fatal to such strength of will as will enable people to control themselves. Clarke says, "Luxury does not consist in the innocent enjoyment of any of the good things which God has created to be received with thankfulness, but in the wasteful abuse of them to vicious purposes in ways inconsistent with sobriety, justice or charity."