[Grieryaliny]

In several suttas we're shown that the features and symptoms of types, odors, looks an such like and a essential section of the instruction is "not to understand and to put on the feelings restrained" Any suggestions about this, I am particually having difficulty understanding the "grasping at symptoms and features." What does this mean, does it mean notion of anything as desirable or undesirable? any guidance and aid could be greatly appreciated Thanks and metta