Is There a Unity to Substances?

Is there a meaningful difference between what you're describing intrinsic finality and the idea of that finality being a cause? So for example, if you think of something like the evolution of biological organisms is what results simply an outcome. Or is it in some way meant to do the things that it does? So are the eyes really foreseeing? Are the eyes meant to see? Or do they simply happen to see is fire meant to heat? or does it simply happen to heat? Yeah, yeah. Well, I appreciate that distinction.