Watershed moments are seldom recognized as such at the moment they occur.  Usually it takes time to discern which way the water is flowing.  I didn’t realize that my young life had reached such a moment with the arrival of my fourth grade teacher.  
“I am Sister Digna, a Sister Adorer of the Precious Blood.  I will be your new teacher,” she said.  With a moniker like that, she didn’t need to add that she was also the principal of St. Joseph’s Parochial School.  Gravitas seemed sewn into her habit, but it went deeper than that.  It was in her sinews.

Sister Digna was my fourth nun, the first to appear in a modified habit, a small black veil over a knee-length, black dress.  Our first three teachers had been younger nuns, wearing the full armature of their order, black veil over white wimple, floor length black habit, accented with a simply stunning red sash—for the Precious Blood, of course.

Sister Digna (It makes no sense to vary my prose and try writing “Digna” instead of “Sister Digna.”  We’re talking ontology here.  It’s got to be “Sister Digna”) was not a large woman.  Even in fourth grade, many of the boys came close to standing eye-to-eye with her.
I remember her looking like Harry Truman in a veil, although in the fourth grade, I would not have known what President Truman looked like.  Kansas classrooms were replete with images of Dwight Eisenhower, the native son who had saved civilization, and most Catholic classrooms had pictures of the martyred Catholic president, but the haberdasher from Independence, Missouri, was not an iconic presence.  To be fair to both Sister Digna and President Truman, I think that I associate their faces because they wore the same sort of wire-rimmed glasses, the type that would be coming back into style a few years after the fourth grade, but then neither the president nor the principal paid much attention to such trends.

The watershed! As we had done most autumns, we took some sort of standardized test at the beginning of the year.  That’s what they were always called.  “Students, remember.  Get a good night’s sleep.  Tomorrow we will be taking the (insert name) Standardized Test.  You need to do well for yourselves and for your families, who have sacrificed so much to give you a Catholic education.”  No matter how the next day’s agenda varied, it always involved someone making a sacrifice.  Sacrifice was always on the schedule.
The watershed was Sister Digna going over the results of the test.  Some sort of paper was briefly put into each of our hands, though the numbers meant nothing to us.  We were essentially supposed to hold them, like our report cards, while a stirring address was made about the advancement of the faith through our efforts.  Sister Digna’s exhortations held an elan that fully justified her leadership role.  She would deliver them, striding up and down the desk aisles, occasionally using her pencil to tap a student on the head.  This is no sad song about being slapped by a sister.  The pencil taps were rhetorical flourishes, the same sort of thing Patton accomplished with his riding crop.

Sister paused when she arrived at my desk.  She hadn’t been enumerating individual results.  This was collective sacrifice, the sort of stuff the Roman martyrs did, but, as she passed each desk, bon mots would drop along with a pencil tap, so that each of us knew ourselves to be personally foresworn in the faith’s great crusade.

I didn’t get a pencil tap, though it was in her hand, obviously at the ready.  “And you, Terry Klein.  You have not been fulfilling your potential.  How dare you carry home more ‘Cs’ than ‘Bs’ to your parents, who have sacrificed...blah, blah, blah.”  Sorry, but the command that followed has crowded out the stanza about sacrifice.  “From now on, you will not produce less than ‘A+’ work.  I will not accept it."

No one had ever told me that I was supposed to be an “A” student.  If someone had, I must have been doodling, examining classroom decorations, or looking out the large windows of St. Joseph’s.  I was thoroughly bored but content with school, until Sister issued her edict of intoleration, the command that altered the course of my life.

Trinity Sunday is a medieval feast, one that, for me, has always seemed tacked onto the end of the Easter Season, like Corpus Christi soon to follow.  But hearing this evocation of the Trinity linked to the command to go forth and baptize, I realize how deeply the mystery that we call Trinity is bound up with the paschal mystery of the Christ, which we enter by means of baptism but which the first disciples directly experienced.

The Church has always insisted that, left to her own devices, she would know nothing of a Father, Son, or Spirit.  Their existence, their identities, do not initially come to us through any process of rational exploration on our part.  Rather, the persons of the Trinity are revealed by the wake that each leaves in the story of the Christ.  Like myself with Sister Digna, the Church needed time to recognize fully whom she had experienced.  It went something like this:

We only know of the one whom Christ called Father, because Jesus made his entire life into a “pleasing and acceptable sacrifice” to the God of Israel.  The existence of Jesus was so utterly centered upon a mysterious other, the one of whom he preached, whom he addressed in prayer, that the when the first Christians became convinced, because of the resurrection, that Jesus was God, they became equally assured that their very notion of God had to be rethought, because Jesus had lived “outside himself,” always “toward another” in action and address.  They would not sacrifice the monotheism of Israel, how could they?  But clearly this monotheism was so much more mysterious than they had imagined.

And when, in the days following the resurrection, they felt the very presence of Jesus stir deep within their souls, and yet they still saw Jesus before them with their eyes, they had no choice but to conclude that the advocate, the witness of whom Jesus had spoken, was now within them, one whom they could address as “Holy Spirit.”

The word “Trinity” never occurs in the sacred scriptures.  The closing baptismal commission of St. Matthew is the only delineation—Father, Son, and Spirit—of the Trinity’s members in the Gospels.  It’s not that the Trinity is made patent in the Gospels; it’s that the Gospels are incomprehensible without the perception of the Trinity.

My life intersected with Sister Digna’s for only nine months, but in that space of time she birthed a new identity for me.  Those meeting me today could know nothing of Sister Digna, unless they were somehow able to plot the arc of my life and see the moment when everything turned.  Like the Trinity, she’s known by her wake.

Or, if someone today were to argue that Sister Digna never existed, besides a few witnesses, I could only point to that pivot in my life, which is incomprehensible without admitting her presence and its effect.  In that sense, Sr. Digna is like the Trinity, a personal mystery known through its mission among us.