"Those most moved to tears by every word of a preacher are generally weak and a rascal when the feelings evaporate"

This quote by Sallust suggests that people who are quickly transferred to tears by the words of a preacher are typically not as strong or ethical as they appear. He suggests that these individuals are only moved by the emotion of the minute, and when the emotion fades, they are left with their true character. This could be interpreted as an alerting to be careful of those who are easily swayed by emotion, as their real character may not be as honorable as it appears. It might likewise be viewed as a tip to be mindful of our own emotions, and to be knowledgeable about how they can influence our decisions and actions. Ultimately, Sallust is recommending that we must beware not to be too quickly swayed by emotion, and to be conscious of our real character.