Simplify the following text for a Grade 19 native English-speaking person.
Original: Some years after the publication of his main work , the Logische Untersuchungen ( Logical Investigations ; 1900-1901 ) Husserl made some key conceptual elaborations which led him to assert that in order to study the structure of consciousness , one would have to distinguish between the act of consciousness and the phenomena at which it is directed ( the object-in-itself , transcendent to consciousness ) .
Simplified: Some years after the 1900-1901 publication of his main work , the Logische Untersuchungen ( Logical Investigations ) , Husserl made some key conceptual elaborations which led him to assert that in order to study the structure of consciousness , one would have to distinguish between the act of consciousness and the phenomena at which it is directed ( the objects as intended ) .