The important thing is to have the right measure of material richness so as not to let the negative aspects of it change us and to help us achieve spiritual richness.

measure 在这里是名词，意思是"程度、量度"，指对物质财富的适度把握。这个词来自动词 measure（测量），引申为"衡量标准"或"适度范围"的意思。