diff --git a/README.rst b/README.rst
index 7b2f932..d9b11fe 100644
--- a/README.rst
+++ b/README.rst
@@ -40,18 +40,18 @@ You really only need to worry about *human*.
 
 Here are all the available arguments and defaults::
 
- human(d, precision=2, past_format='{0} ago', future_format='in {0}'):
+ human(date_time, precision=2, past_tense='{} ago', future_tense='in {}'):
 
-d
+date_time
  datetime object to make into human readable, required
 
 precision
  control how verbose the output should look, optional
 
-past_format
+past_tense
  format string used when d is a past datetime, optional
 
-future_format
+future_tense
  format string used when d is a future datetime, optional
 
 
@@ -99,16 +99,16 @@ Now we will document how to use delta2human and delta2dict::
  # create a dictionary out of the timedelta
  print delta2dict( delta )
 
-Example past_format and future_format keyword arguments::
+Example past_tense and future_tense keyword arguments::
 
  output1 = human( PAST,
-   past_format = 'titanic sunk {0} ago',
-   future_format = 'titanic will sink in {0} from now'
+   past_tense = 'titanic sunk {0} ago',
+   future_tense = 'titanic will sink in {0} from now'
  )
 
  output2 = human( FUTURE,
-   past_format = 'titanic sunk {0} ago',
-   future_format = 'titanic will sink in {0} from now'
+   past_tense = 'titanic sunk {0} ago',
+   future_tense = 'titanic will sink in {0} from now'
  )
 
  print output1
diff --git a/ago.py b/ago.py
index 0ef8d2e..54a484b 100644
--- a/ago.py
+++ b/ago.py
@@ -2,7 +2,7 @@ from datetime import datetime
 from datetime import timedelta
 
 def delta2dict( delta ):
-    """return dictionary of delta"""
+    """Accepts a delta, returns a dictionary of units"""
     delta = abs( delta )
     return { 
         'year'   : delta.days / 365 ,
@@ -13,10 +13,10 @@ def delta2dict( delta ):
         'microsecond' : delta.microseconds
     }
 
-def delta2human(delta, precision=2, past_format='{0} ago', future_format='in {0}'):
-    """return human readable delta string"""
-    the_format = past_format
-    if delta < timedelta(0): the_format = future_format
+def delta2human(delta, precision=2, past_tense='{} ago', future_tense='in {}'):
+    """Accepts a delta, returns a human readable delta string"""
+    the_tense = past_tense
+    if delta < timedelta(0): the_tense = future_tense
     d = delta2dict( delta )
     hlist = [] 
     count = 0
@@ -28,12 +28,12 @@ def delta2human(delta, precision=2, past_format='{0} ago', future_format='in {0}
         hlist.append( '%s %s%s' % ( d[unit], unit, s ) )
         count += 1
     human_delta = ', '.join( hlist )
-    return the_format.format(human_delta) 
+    return the_tense.format(human_delta) 
 
-def human(d, precision=2, past_format='{0} ago', future_format='in {0}'):
-    """Pass datetime we will return human delta string"""
-    delta = datetime.now() - d
-    return delta2human( delta, precision, past_format, future_format ) 
+def human(date_time, precision=2, past_tense='{} ago', future_tense='in {}'):
+    """Accepts a datetime, returns a human readable delta string"""
+    delta = datetime.now() - date_time
+    return delta2human( delta, precision, past_tense, future_tense ) 
 
 if __name__ == "__main__": 
     from test_ago import test_output
diff --git a/test_ago.py b/test_ago.py
index b673b9b..422b6c5 100644
--- a/test_ago.py
+++ b/test_ago.py
@@ -41,17 +41,17 @@ def test_one_day_singular():
 def test_two_day_plural():
     assert 's' in delta2human( timedelta(2) )
 
-def test_past_format():
+def test_past_tense():
     output = human( PAST,
-      past_format = 'titanic sunk {0} ago',
-      future_format = 'titanic will sink in {0} from now'
+      past_tense = 'titanic sunk {} ago',
+      future_tense = 'titanic will sink in {} from now'
     )
     assert 'titanic sunk' in output
 
-def test_future_format():
+def test_future_tense():
     output = human( FUTURE,
-      past_format = 'titanic sunk {0} ago',
-      future_format = 'titanic will sink in {0} from now'
+      past_tense = 'titanic sunk {} ago',
+      future_tense = 'titanic will sink in {} from now'
     )
     assert 'titanic will sink in' in output
 
@@ -69,11 +69,11 @@ def test_output():
     print '\nTesting past:\n'
     print delta2dict( PAST_DELTA )
     print 'Commented ' + delta2human( PAST_DELTA, 3 )
-    print human( PAST, past_format = "Commented {0} ago" )
+    print human( PAST, past_tense = "Commented {} ago" )
 
     print '\nTesting future:\n'
     print delta2dict( FUTURE_DELTA )
     print 'Shutdown ' + delta2human( FUTURE_DELTA, 3 )
-    print human( FUTURE, future_format = 'Shutdown in {0} from now' )
+    print human( FUTURE, future_tense = 'Shutdown in {} from now' )
     print ''