This is what is called the
conditional positive regard. It is the opposite of the unconditional positive
regard and it means acknowledgment under certain condition. It can be both
positive and negative. Positive when nurtures growth and negative when for example
child comes out as homosexual and his parents start encouraging him to seek medical
help unless the their child wants them to stop providing positive regard.
It was possible because it helped him navigate in territories that were completely unknown to him. Thanks to it, he could determine where his ship was based on the position of the sun and the time of the day and he used this to navigate all the way to India.
He sailed there on his fourth and final voyage to the New World on May 11, 1502. I hope this helps, and you can ask me for a specific if you need! :)
East because it is going across the Atlantic ocean