κατανοητέον
From LSJ
θεοῦ θέλοντος κἂν ἐπὶ ῥιπὸς πλέοις → if God willed it, you could sail even on a straw mat | God willing, you may voyage on a mat
English (LSJ)
A one must observe, learn, Pl.Plt.305c, Porph.Marc.27; one must consider, πάλιν περί τινος Ph.1.83.
Greek (Liddell-Scott)
κατανοητέον: ῥημ. ἐπίθ., πρέπει νὰ μάθῃ τις, νὰ παρατηρήσῃ, Πλάτ. Πολιτ. 305C.