What is foreseeability and what is the test for foreseeability?

It is clear that foreseeability is but one factor to be weighed in determining whether a landowner owes a duty in a particular case. "In this balancing process, foreseeability is an elastic factor. (2 Harper & James [Law of Torts (1956) ] 18.2, at p. 1026.) The degree of foreseeability necessary to warrant the finding of a duty will thus vary from case to case. For example, in cases where the burden of preventing future harm is great, a high degree of foreseeability may be required. [Citation.] On the other hand, in cases where there are strong policy reasons for preventing the harm, or the harm can be prevented by simple means, a lesser degree of foreseeability may be required." (Gomez v. Ticor (1983) 145 Cal.App.3d 622, 629-630, 193 Cal.Rptr. 600.) Thus, foreseeability is a somewhat flexible concept.