The tender sentiment of the 'one and only' has less to do with constancy of heart than with singleness of opportunity. - B. F. Skinner

One may take the line that metaphorical devices are inevitable in the early stages of any science and that although we may look with amusement today upon the “essences,” “forces,” “phlogistons,” and “ethers,” of the science of yesterday, these nevertheless were essential to the historical process. It would be difficult to prove or disprove this. However, if we have learned anything about the nature of scientific thinking, if mathematical and logical researches have improved our capacity to represent and analyze empirical data, it is possible that we can avoid some of the mistakes of adolescence. Whether Freud could have done so is past demonstrating, but whether we need similar constructs in the future prosecution of a science of behavior is a question worth considering.

Let men be happy, informed, skillful, well behaved, and productive.

The amateur doesn't appreciate the need for experimentation. He wants his experts to know.