Passage
If ye know these things, blessed are ye, if ye doe them.
John 13:17 (GNV)
Nearby Context
John 13:15 For I haue giuen you an example, that ye should doe, euen as I haue done to you.
John 13:16 Verely, verely I say vnto you, The seruant is not greater then his master, neither the ambassadour greater then he that sent him.
John 13:17 If ye know these things, blessed are ye, if ye doe them.
John 13:18 I speake not of you all: I know whom I haue chosen: but it is that the Scripture might be fulfilled, He that eateth bread with me, hath lift vp his heele against me.
John 13:19 From henceforth tell I you before it come, that when it is come to passe, ye might beleeue that I am he.
Study Lenses
The verse centers on "things" and "blessed". It is saying that the verse draws attention to "things" and "blessed", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "Verely verely I say vnto you The..." into verse 18's "I speake not of you all I...", so "things" and "blessed" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "things" and "blessed" with trust shaped by these words, not by a vague optimism outside the passage.