This applies to Father Hecker's case also, for he was of a bent of mind truly philosophical, and he has placed on record the similarity of his philosophical difficulties with those of Brownson.
But in addition to philosophical questions, and far more pressing, were to Isaac Hecker the problems arising from the mystical occurrences of which his soul was the theatre.

Were these real?
that is, were they more than the vagaries of a sensitive temperament, the wanderings of a sentimental imagination, or, to use Father Hecker's own words, "the mere projections into activity of feelings entirely subjective; mystical impulses towards no corresponding objective realities, or, at any rate, with objects which it is not possible to bring into the field of the really knowable?
Some will admit that religious feeling is as much a verity as any other part of human consciousness, affirming, however, the subjectivity of all purely spiritual life; and no more can be said, they insist, for the principles, metaphysical and logical, with which they are associated in the spiritual life of man.

Now, such a theory never leaves the soul that is governed by reason at rest.

The problem ever and again demands solution: are these yearnings, aspirations, unappeased desires, or religious feelings--the ruling traits of the noblest men and women--are they genuine, real, corresponding to and arising from the reality of certain objects external to the soul?
I think that in the solution of this problem Dr.Brownson fought and won his greatest victory; at any rate, it was to me the most interesting period of his life.

No wonder, since I had the same battle to fight myself, and it was just at this epoch that I came into closest contact with him.