How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?

Mendel explained that it is possible that a trait is inherited but not expressed in an organism through his experiments on pea plants. He proposed that each trait is controlled by two factors (now called genes), one inherited from each parent. These two factors may be identical or different, depending on the parentage. If the two factors are identical, the trait will be expressed. However, if the two factors are different, only one of the traits will be expressed, and the other will be hidden. This hidden trait is not lost but is inherited by the offspring.