"The intervals may be counted, not only from episodes of violence, but from eruptions of an emotional nature."
An emotional agitation may be religious, economic, or political in nature. "An emotional agitation is normally a juncture of difficulty, and the interval progresses from difficult to easy." It is hard to date the genesis of an emotional agitation accurately. The starting point is not nearly as clear as bloodshed in a revolution or other physical agitation. Emotional agitations have an idiosyncrasy that Lindsay described: "While the delayed effect after a physical agitation is largely confined to the country where the violence occurred, the repercussions following an emotional outburst can leap across national boundaries." He found that these repercussions were most likely to spread if one or more conditions were met. If the agitation were based in an important locus of culture, such as 15th-century Florence, Italy, the effects were more likely to spread across borders. Lindsay wrote that the intensity of an agitation, more than its content, is a key factor. Finally, if the event was radically different from the accepted order of things, it was likely to spread regardless of borders. Another idiosyncrasy: "As a rule, though not invariably, success for an idea is achieved after the second emotional agitation of a series directed toward the same end."
The founding of the Christian church can be thought to have dated from the crucifixion of Jesus Christ. Lindsay wrote, "The ministry of Jesus Christ was an emotional agitation and the crucifixion was a purge."
Lindsay wrote, "Since the crucifixion is classified as a purge, the progression runs from easy to difficult; both Rome and the Jews were due to undergo misfortune." This progression is from the viewpoint of the Romans and Jews. Using A.D. 30 as the most probable date of the crucifixion, counting forward 36 years to the year A.D. 66 saw the Jews revolt against Roman rule. Vespasian laid siege to Jerusalem in A.D. 68, and the city fell to Titus in August–September of A.D. 70 at the 40-year interval after the purge, or crucifixion.
The Romans suffered misfortunes too. If A.D. 30 was definitely the year of the crucifixion, then the Great Fire of Rome, in A.D. 64, was one year too early to be attributed to the progression from easy to difficult. But given the relative uncertainty of the date A.D. 30, the Great Fire of Rome deserves mention. The fire burned for five-and-a-half days and only 1 of 14 districts of Rome escaped the fire. Lindsay writes: "The one that could have been predicted was the death of Nero in June 68, and even more typically, the extinction of the Julian-Claudian house. The repercussions in the case were more extraordinary than usual, for three emperors swiftly followed Nero in the 'long but single year,' as Tacitus called it."
Lindsay wrote, "Count the 55-year interval from the crucifixion in A.D. 30 and you come to 85. A bitter quarrel broke out between Emperor and Senate when Domitian had himself appointed censor for life." The climax was reached at the 66-year interval in September of A.D. 96 when Domitian was assassinated.
As for the opposite progression, from difficult to easy, Lindsay wrote, "The 64–69-year interval from difficult to easy after an important emotional agitation has normally signaled a period of remarkable prestige or progress. Sometimes this count denotes the start of such an era. In that case, the good fortune lasts another 64–69 years, and this may be stretched to 80 or 90 years under certain circumstances—when for example there is second agitation to count from."
To sum up, Lindsay explained his views best when he wrote: "Emotional agitations are not the cause of subsequent success, but merely an outward sign of little understood forces which operate under the surface."..."Arguments are never won by logic, merit or even performance: men are incapable of judging such points objectively."..."The intervals operate by influencing the mind of a man in solitude no less than by arousing the crowd through the overworked bogey of "mass psychology."