What is the meaning of [You can lead a horse to water but you can’t make it drink]

Tom Robbins, Jitterbug Perfume (1984),”It is so amusing the way that mortals misunderstand the shape, or shapes, of time. … In the realms of the ultimate, each person must figure out things for themselves. … Teachers who offer you the ultimate answers do not possess the ultimate answers, for if they did, they would know that the ultimate answers cannot be given, they can only be received.”,Martin H. Manser (2007). The Facts on File Dictionary of Proverbs. Infobase Publishing. p. 304. ISBN 978-0-8160-6673-5.