Towards the end of chapter 6 of his Fawā’id, after going over the complexities of various kinds of routes and course-plotting options, Ibn Mājid explains:
I have made distinctions (farraqtu), because the different skills (‘ulūm, “sciences”) are like weapons: sometimes you need a bow and sometimes a sword, sometimes a spear and sometimes an ax or a dagger, and yet, for all this, you may never be dispensed of using a knife.
The explicit point seems to be that every skill, as a subdiscipline of knowledge, has its own irreplaceable and particular application, and that it is necessary to have a rounded preparation, because, as he puts it later, borrowing a saying from Imam ‘Ali: “man is the enemy of anything he is ignorant of,” or rather, given the context, “man is at war with everything he is ignorant of” (al-insān ‘aduww mā jahilahu). That is (and we must put it in the context of piloting a ship through the ocean and having to land safely thousands of miles away), everything we ignore is a hostile prompt to catastrophic failure. And the obvious way to be prepared, or armed, is to acquire the panoply of knowledge required by our respective field.
The implicit point is in that initial “making distinctions”, associated to terms like farq, “distinction, discrimination, severance”, and furqān, an epithet of the Qur’an meaning “a criterion”. As it happens, this root-meaning of division and discernment is exactly the same of the English-Germanic skill, and also of Latin scientia. The suggestion that science and skill have a common origin in discernment/dissection should give us pause now, as it would be better developed in another post.
So now, instead, going back to the image of waging war against ignorance, we can see how the mighty ancient saying is so much better when applied in science than in politics: Divide et impera! or in Arabic, Farriq tasud!, discern and you shall rule. [JA]