Knowing (ειδοτες). Second perfect participle of ειδον (οιδα), giving the reason for the previous exhortation to glory in tribulations. He gives a linked chain, one linking to the other (tribulation θλιψις, patience υπομονη, experience δοκιμη, hope ελπις) running into verse Romans 5:5. On δοκιμη, see 2. Corinthians 2:9.