The fate line, also called the line of Saturn, runs vertically up the centre of the palm toward the middle finger, and the tradition reads it for career, direction and the degree to which a life is shaped by circumstance rather than by choice; its absence, which is common, is read for a life of one's own making or, in less generous readings, for a lack of direction. The line is not present in all hands, and its variability is one reason different palmists give quite different readings of the same palm. The general point applies to the whole art: because the interpretive vocabulary is large and the features are ambiguous, two competent practitioners of the same school can and do disagree, and there is no procedure within the tradition for settling which is right.
In the Indian tradition of samudrika shastra the line is called bhagya rekha, the line of fortune, and the Western and Indian schools broadly agree on what the line marks even where their vocabularies differ. Cheiro's system reads the line's point of origin as a further layer of meaning: a fate line rising from the life line itself is read as success built by personal effort against difficult early circumstances, while one rising instead from the Mount of Moon, at the base of the palm opposite the thumb, is read as success dependent on the help, favour or caprice of other people. As with the rest of the art, no controlled study has found that any feature of the palm predicts a person's career or circumstances, and the line's meanings are best understood as traditional attributions rather than as forecasts.
Sources Les Mysteres de la MainAdolphe Desbarrolles with Palmistry for AllCheiro (William John Warner)