I've scoured the books of history looking for trends - why did this person succeed, when that one failed? Why did this movement shape the world, while that one died out? Why did this nation win, and that one lose?

Some people think accidents explain history. Perhaps accidents explain some of history, but certainly not all. You see common virtues among those who succeeded, and frequently you see common vices among those who failed.

Of the common virtues, the successful seem to have an immense amount of loyalty and reverence for the people that "got them there," revering and celebrating them even as they bring more and more people to their banner. The people who break from their early friends and supporters usually end poorly, in an isolation of their own making.

You can see this with two men that had the biggest impact on their respective cultures - Muhammad in Arabia, and Hideyoshi in Japan.

Both men were low born, but came to be hugely influential. There are a number of similarities in their stories. They both found and married an exceptional, charismatic, diplomatic, high born, highly intelligent woman relatively early in their careers. The wives of these men - Khadijah to Muhammad, Nene to Hideyoshi - were their first, most passionate, and largest supporters when few else believed in them.

But that's where the similarities end. Muhammad went on to be the Prophet of Islam, united the previously warring Arabic tribes, conquered Mecca from the hostile Quraysh, and then all of the Arabian Peninsula. The series of law, decree, and messages he spread are one of the most enduring in the world. His own family went on to do well, his three daughters all marrying future Islamic Caliphs, and leading to a long and healthy bloodline and genealogy.

Hideyoshi, of course, became the Second Great Unifier of Japan, finishing Oda Nobunaga's work. He'd risen from sandal-bearing house servant to one of the greatest diplomats and generals in Japanese history. But after being named Kampaku - Grand Regent of All Japan - he led the foolish Korean expedition, executed his nephew and ready successor out of pettiness, and died leaving his family and values with an unstable power vacuum. Not long after his death, Japan broke out in Civil War, with the Tokugawa faction destroying Hideyoshi loyalists. Hideyoshi's bloodlines were exterminated and erased from history.

I've spent a lot of time studying Hideyoshi Toyotomi. The first 50 years of his 60 year life are some of the most luminous and impressive of all time. But the last 10 years of Hideyoshi's life are an unmitigated disaster, the most ridiculous and extreme blundering imaginable.

I've come up with a few different hypotheses about where Hideyoshi went wrong. But certainly - this is key - he paid dearly for his lack of loyalty to the people closest to him at the end of his life.

Hideyoshi had a number of people who helped him build early in his life. Nene, his wife, was key to that. But later, he married a young princess, Yodo-dono, who was very beautiful but didn't have the same wisdom, intelligence, and diplomacy that Nene did. But Hideyoshi progressively started ignoring Nene and favoring the young princess.

It was the beginning of the end. Yodo-dono eventually alienated Hideyoshi from his sister, who had also been extremely loyal and helpful to him. When Yodo gave birth to a son of Hideyoshi's, she demanded for Hideyoshi to execute his sister's son, his nephew who was a smart and capable boy.

Things unravelled quickly. Hideyoshi went on to execute one of his top advisors, Sen no Rikyu, and marginalized a lot of his most loyal supporters. When the Toyotomi Civil War broke out after his death, many of his former supporters defected to the rival Tokugawa camp - and the Toyotomi were destroyed forever.

Muhammad wound up in a similar situation. After Khadijah's death, Muhammad took other wives - but he handled things 180 degrees differently from Toyotomi. He showed immense reverence and loyalty to the people who had gotten him there.

Muhammad's later young wife, Aisha, was jealous of Khadijah's role in his life. Aisha asked Muhammad, wasn't she better than Khadijah? She'd become jealous when he visited her friends and relatives to take care of them.

Muhammad was obviously enchanted with Aisha, but he held more strongly to his loyalty and reverence for Khadijah, saying, "She believed in me when no one else did; she accepted Islam when people rejected me; and she helped and comforted me when there was no one else to lend me a helping hand."

This consistency of loyalty and reverence to the people that got him there inspired and moved Muhammad's followers - including the ones who joined later. Truly, it's a noble trait. Whereas Hideyoshi's unraveling and betrayals of his closest people led many of his generals to defect to the enemy.

It's not even about personal gain - it's about a sense of right and wrong. A short-sighted man would think rewarding your new supporters would engender the highest level of loyalty in them, but Hideyoshi proved that false. By taking great care of the people who elevated you from the beginning, you build a stronger foundation that's worthy of respect and admiration - you stay close with your early supporters, and create an atmosphere of calm trust and strength among new supporters.