In the Greek text Paul refers to the law as being a pedagogue.
A pedagogue (or custodian) was a servant responsible for looking after children until they reached maturity.1 Functioning in a similar way as a nanny, they would teach basic morals and manners. With the law being a custodian, the emphasis falls on its temporary nature.2 It was intended for a limited time only.3
24 So then, the law was our guardian until Christ came, in order that we might be justified by faith.