During the summer before Harry Potter's third year, he had a dream. In it, he became a snake and witnessed a Muggle being murdered.
That snake was later confirmed to be Nagini, one of Voldemort's Horcruxes. Albus believed it was because Harry had some sort of connection with the Dark Lord, and that connection grew ever closer after Voldemort's resurrection.
This dreamlike vision was called "spirit wandering" in the Middle Ages. It was not actually a dream. This ability had once been widespread among shamans and Druids. It could also be understood as something related to "nature": people would usually possess animals, allowing them to ignore distance and time. Leeds had once borrowed the eyes of Barnaby's dog, Dexter, and nothing had gone wrong then.
Though Crups were close to wizards, they were loyal to their masters. Dexter was friendly toward Leeds, but he understood that she was not his owner. He could reclaim his body at any time and risk his life to protect Barnaby whenever Barnaby was in danger.
Artemis, meanwhile, belonged to Leeds. She was a well-trained owl who would not do anything her owner forbade, not even seize control of her own body again.
Besides, Artemis was very clingy. That made her adorable as a pet, but after entering another realm, it was better to preserve the independence and integrity of each other's souls. Of course, Pomona had not known so much back then. After returning to the castle, Snape brewed Leeds a cauldron of Potions. It was practically an upgraded version of a Sleeping Potion.
When Tycho Dodonus was still at university, he had been influenced by Descartes. He trusted his own experience rather than the schoolbooks, and from then on, he believed his abilities surpassed those of ancient and modern makers of star charts.